The matter was reported to the commissioner.
The commissioner reported the matter.
mean different things. To change to the active voice while retaining the meaning would be something like this:
The commisioner received the report of the matter.
This is a more verbose way to say it, and it is a more complicated and less natural construction. I woud recommend using the original passive example. The passive voice is just as grammatically correct as the active, and in this case it better suits the semantics of the sentence.
If you are able to specify a subject of the sentence, such as "he" or "they" or "the deputy", then you could reconstruct the sentence like this:
He/they/the deputy reported the matter to the commissioner.
This doesn't retain the original meaning because it introduces a subject that was never mentioned in the original sentence, but it may suit your purposes well enough.