If your OPT has expired, any continued employment would be unlawful. Also, your F-1 status expires 60 days after the expiration of your OPT.
Being out of status means you are removable (deportable). Being out of status can preclude you from getting future visas to enter the US.
It is very unlikely that you would be able to return to the Untied States if you leave. I assume your student visa has expired, so you probably have no document to return with.
The above is not intended as legal advice. You should seek counsel.