All of a sudden tv display too bright?

A couple days ago I switched my av cables out to play my xbox and then back again to the tv, and the display was really bright! I tried lowering the brightness but it didn't help? It's like the color white shows up weird on the tv, I can't even watch cartoon shows because everything blends into a bright white mush! My tv is a 32" Olevia LCD flatscreen. Can anyone help?