A personal loan was paid back to me in check the account was closed amt 800.00 how can I get my money

Did you report it to the Police? It's illegal to write a check on a closed account.

And, of course, sue in Small Claims Court.

As Judy said this was illegal. You can threaten to go to the police if he doesn't pay, but you need to mean it. Otherwise you sue. You have the rejected check as proof.