unfair account closure

Hi to all. I think that lichess has closed one account to someone that never never has cheated in his life. I think that is something to do to take back his account. Can anybody tell me wat to do to take back the account?

if u closed it urself, then enter the username then it says: you have closed you account before. if u didnt and it gets closed, idk how to fix it

See lichess.org/contact#help-appeal
Accounts can be closed for other types of misbehavior.