If you think someone has access to your account, use a device you trust to secure it.
Change the password to a new, unique password that you have not used on another service.
Sign out other sessions or remove unfamiliar devices if the service provides that option.
Check the recovery email address, phone number, trusted devices, forwarding rules, connected apps, and other security settings for changes you did not make.
Enable multi-factor authentication and make sure the recovery methods belong to you.
Check recent account activity for messages, posts, purchases, password changes, or other actions you did not make.
If you cannot regain control of the account, use the service's official recovery process rather than paying someone who claims they can recover it for you.