The game crashed when i was at champ selection screen... then when I tried to restart the game, i couldn't log into LoL. I tried rebooting my PC and restarting the game but the client keeps getting not responding error when I tried to log into LoL. Is it that my account got stuck?

Help!

I remember having heard about this once. I didn't stick around to see the fix though.
I recommend logging back in after a few hours. Or better yet, restart.

It is possible that the client hasn't properly closed down, and so a copy of it is still running in the background. Since the launcher is a separate entity, it can be launched as normal. So restarting normally helps.

i tried again after about 15 - 20 minutes, it worked!

Thanks Xoco!

Generally you only need to wait 15-20 seconds.

If it seems like its taking a long time, open up the task manager and force quit any LoL process (mostly lol.launcher).