I was suspecting that someone stole my accpunt what should I do

I saw some games today but ı didnt played them

Change your password

I think you should do at least the following two things:
- change your password
- check sessions on lichess.org/account/security and revoke those that seem suspicious to you.
I don't know if you should also report to lichess, maybe somebody else knows?

Additionally, as a general practice, setup 2FA on all accounts that support it. Lichess supports it. lichess.org/account/twofactor

I use an app for Android called Authy to keep track of all my 2FA tokens.

authy.com/what-is-2fa/