There are holes everywhere I look. I'm in St Ives in Cornwall, strolling around the Barbara Hepworth Sculpture Garden, a thickly growing, almost tropical space where tree, plant, shrub and sculpture live in perfect harmony. A circular opening in a bronze oval pulls my eye through it to a second sculpture hovering amid wet green leaves. Another bronze shape is big enough for me to enter. Inside, I look up at the sky through a gaping hole, into the drizzle that's spattering down on to the bronze floor. Every vista seems framed by these holes, like eyes, like caves.  From 1949 until her death in 1975, Hepworth lived and worked at this place, which now serves as a museum. Her studio stands in the garden: peer in and you can see the tools she loved to use, all her chisels, saws and hammers, as well as her white work apron and a set of unfinished works, geometric stone spheres as pure as they are precise.  The feeling you get, though, is of melancholy, perhaps because the story of Hepworth's studio is so horrible: this sculptor, born in Wakefield in 1903 and recognised as one of the outstanding British artists of the 20th century, died in a fire here. It is wonderful to meander around this garden, to see her work emerging from and disappearing into the wildlife – yet the sadness and violence of her last moments keep crowding in.  Other things, too, are sad about Hepworth's last years. She was not exactly forgotten when she died; in fact, she was widely honoured. But art had changed. Young artists in the 1970s were questioning the very idea of "sculpture" that Hepworth and Henry Moore, her friend and contemporary, stood for. Gilbert and George performed The Singing Sculpture, posing as surreal living statues singing Underneath the Arches, while Richard Long went for walks, arranged a few pebbles along the way, and declared it sculpture. The idea of sculpture as an intensely carved and crafted object was fading, leaving this veteran artist adrift in St Ives.  Today, however, she is being reclaimed as a hero of British art. The Hepworth Wakefield, an art gallery designed by David Chipperfield to house a permanent collection of her works, opens this month. The Hepworths on view here will be plaster sculptures, rarely seen before; but perhaps just as important is the fact that they will be seen next to exhibitions of contemporary art.  Hepworth's qualities are being recognised elsewhere, too. Bicentric Form, a monolith with a humanoid head and a hole that resembles a shoulder wound, currently takes pride of place at Tate Britain. Among other Hepworths on show is Sculpture With Profiles, a curvaceously hewn piece of white alabaster on which eyes and noses have been etched.  Hepworth, clearly, is back. But what's behind this rediscovery? Is her significance being exaggerated at a time when the wheel of art-world fashion happens to have turned back towards early 20th-century Britain? Perhaps the answer can be found in the places where Hepworth lived and worked, and among the landscapes that shaped her. So I set off to find out.  In Wakefield, I stumbled across Castrop Rauxel Square. It was late afternoon, and the sun had turned the houses golden. In the centre stand two public sculptures. One is a statue of Queen Victoria, the other a family of abstract personages by Hepworth, taken from her larger work The Family of Man and placed here as a monument after her death. There is no better place to see what Hepworth achieved than here, with its colliding worlds: abstract art versus the Victorian age. In 1903, Victoria was very recently dead. Wakefield was at the centre of a coal-mining district whose own demise was to come in the 1980s. Hepworth's father was an engineer, who took her on his work trips through the West Riding by car. In those days, the town, as well as being surrounded by pits, had brick terraces, smoggy factories and tall chimneys billowing smoke.  It was, above all, a landscape of work. Hepworth said the Yorkshire countryside that she saw with her father influenced her deeply. At the Yorkshire Sculpture Park, not far from Wakefield, you can fully understand the rolling, dipping character of this landscape – and see The Family of Man. Its vertical figures, formed of squares and ovals perforated with holes and slits, are as silent and brooding as the stone heads on Easter Island.  Now that the mines, slag heaps and pit workings have given way to sculpture parks, it's worth remembering that the town and countryside that formed Hepworth were industrial and sombre. Everyone worked – relentlessly. That is the key to understanding Hepworth: both she and Moore rediscovered sculpture as work, as manual labour.  Hepworth's carved stones in Tate Britain seem tended, nurtured, you might almost say parented. It was daring for a young woman to study sculpture just after the first world war. It was still more extraordinary for a woman to be one of a group of artists who revived the art of direct, physical carving. The grand artists of the Edwardian age had moulded their figures and then paid stonemasons to do the dusty hard graft: Hepworth, Moore and the brilliant Henri Gaudier-Brzeska (killed in the first world war) did their own carving and learned the secrets of stone, the way it can break and open and release magic forms.  The sea cave and the sand dune  That is the lasting appeal of Hepworth's art. Her stone sculptures make you want to hold them (you cannot). Their exteriors are smooth yet never cold: the round, irregular, pierced shapes she releases from stone seem infused with life. Her abstract forms have a perfection and a beauty that echo nature, the human body, and all that is curving and can be pierced. There is something of the sea cave and the sand dune about them.  In the 1920s, this brilliant young artist moved towards a completely abstract style. A decade later, she and her husband, the abstract painter Ben Nicholson, worked in a community of radical artists in Hampstead, London, and exhibited with the great Dutch artist Piet Mondrian. The two then moved to St Ives with their three children, and Hepworth started to carve wood as well as stone, adding taut strings, as if the world were a musical instrument to be played. Her rotund, elegant wooden creations suggest waves curling over rocks perforated by the sea. St Ives, after all, is like a natural sculpture. Minute by minute, you can see rock being carved by the elements, out on that headland that divides the town in two.  Back at the Hepworth museum, a beautifully reconstructed living room showcases fine examples of Hepworth's art. Holes open each piece out. There's a carved prototype for Single Form, her memorial to Nobel peace prize winner Dag Hammarskjöld; the full-size version can be seen at the UN in New York, a deep, round dimple in it rather than a hole. Here, too, is the carved wooden version of her sculpture Epidauros, a rotund, bulging form with holes tunnelled through it sideways and from above. Above the sea near St Ives railway station sits a bronze version of Epidauros, its cave-mouth framing a view over the sea. Epidauros (the title refers to an ancient Greek theatre) is a work of aspiration and longing, an expression of the human desire for meaning common to Greek tragedy and abstract art.  Hepworth worked right up to the end of her life, and her studio is a shrine to hard work. It's what made her tick. That she died here seems meaningful after all: not just a grotesque tragedy but the death of a worker-artist, a craftswoman whose vision was in her hands. Wood was easier to work than stone, and allowed her to keep working even as her health failed.  What are the secrets of artistic lives? We love to imagine them as dramas of sex, drugs and politics, but Hepworth's drama was physical: the daily tending of materials to produce beautiful forms. Her work resounds with sensual beauty and pure contemplative labour. Harmonies, dreams, the British landscape and its very geology – if you could pluck the silent strings of her sculptures, all these things would ring out.  • The Hepworth Wakefield opens on 21 May. Details: hepworthwakefield.org
After dominating early 20th-century sculpture, Barbara Hepworth fell out of fashion. Why is she now being resurrected? Jonathan Jones looks for clues in Yorkshire and Cornwall