Stuck on fullbright. Help!

So. the other day i was playing on CA and everything was working fine. Then the next day i went on and noticed it was on fullbright. the options wouldnt let the brightness get turned down any lower and when i turn on full bright on a hack it would just stay the same (the brightness wouldnt change at all). If you could help me with this problem that'd be great. Its really starting to get annoying.