Riot, I want to get my nick back
Riot, please return my Account because I did not play when I forbade him
Riot, please return my Account because I did not play when I forbade him
If you truly believe your account name was suitable then submit a support ticket, without knowing what your previous name was we can't even give you any help or advice on it.
Good luck.
We need more information to discuss this with you - was the name changed for being inappropriate, was the account banned, etc.
If the account was banned, and the ban was not for security reasons or in error, then the name will be held up until the normal timeframe for name release - namely 2 years 6 months from last activity for a level 30 account (this may change soon given the leveling updates).
If the account was banned for security reasons or the ban is found to be in error, you will resume the account upon resolving the security issue with Riot Support.
If the name was changed for being inappropriate, you are welcome to discuss with Riot in a support ticket and they can look into if it may be borderline acceptable.