This happened to a friend of mine last May ane he still can't figure out what went wrong.
First he got this letter.
We'd like to inform you that due to repeated or severe violations of our Community Guidelines (https://www.youtube.com/t/community_guidelines) your YouTube account has been suspended.
After review we determined that activity in your account violated our Community Guidelines, which prohibit spam, scams or commercially deceptive content (https://support.google.com/youtube/answer/2801973?hl=en).
He had never used his YouTube account, didn't even know he had one. He has a gmail account so he assumed youtube probably came with that but his gmail has two factor authentication and nobody attempted to log into his account via gmail so it couldn't be a hacking situation.
He had never logged into YouTube, never posted a video or even viewed one, let alone made a single comment. When he wrote in to ask what in the world that was all about they never did tell him. Just wrote this instead ---
Hello,
Thank you for your account suspension appeal. We have decided to keep your account suspended based on our Community Guidelines and Terms of Service. Please visit http://www.youtube.com/t/community_guidelines for more information.
Please do not respond to this email. Replies to this email will not be processed. Please refer to our Help Center for more information.
Sincerely,
The YouTube Team
That's what I got too. They won't look into my appeal because it was for copyright claims, yet Ic an't know what or from who... no ability to counter.