A YouTube Help thread has confirmed reports form Google that they have suspended many YouTube accounts completely by mistake.
Liz from YouTube support said in the thread:
We've heard many of you tell us your YouTube Account was suddenly suspended this week, even though you didn't have strikes against your Account and hadn't done anything to merit suspension.
Some YouTube Accounts were suspended this week in error. These Accounts have been reinstated and all of the videos in the Accounts should be restored.
We're you suspended this week?
Liz adds that some who have been reinstated still might have their videos showing in their YouTube accounts. If so, she asks you to post in the thread and make sure to share your YouTube channel or username so they can track it down.
Forum discussion at YouTube Help.