What do I do if I was convicted of a felony for breaking into my parent’s house and stealing 4 of my father's guns in 1992?

You may be able to get the case dismissed, but it would not be effective for state, local, county employment or for licensing boards to whom you will still have to disclose the conviction. Also, if you are charged with theft in the future even a petty theft could be charged as a felony petty with a prior.