Account hacked please help

Please help.

At 1:55am on 1/4/2020 I received an email that my account email had been changed. The email that it was changed to was aerowaero@yahoo.com, however, when logged into my Plex account the displayed email is:

YGoMkfbykem_wSMBWHxz@example.com

I do not know either of these emails. My account has been compromised. I received another email with a link to change my password, but the link was expired. When trying to change the password or delete the account, it seems I’m unable to because I cannot use my set password. Please help!