Hmmm. Have you checked your email? You should receive an email stating why you were given a suspension, as well as the duration. The email may have been placed in your spam or junk folder, so be sure to check there as well. If you still don't see it after about a day, submit a Ticket to Riot Support and one of the specialists will get back with you to let you know why you were suspended.
They do temporarily suspend accounts during the process of recovering a compromised account, so if there was anything further to do with that, it is possible that was why it was locked up again.
As far as punishments going from nothing to ban... that's rather rare. It can happen in the cases of people found to be breaking the terms of use via hacking/scripting/elo boosting, depending on the severity of what was done. It can also be done in case of extremely negative behavior, typically involving a significant amount of hate speech.
I find the two month ban to be rather odd. None of their punishments are for two months. They have the 10 game and 25 game chat restrictions, and then the 14 day temporary suspension, and finally the permanent suspension.
Best of luck, and hopefully, your email will clear this up to be a minor matter, so you can be back on the rift in no time!
