Broken Sony TV! Help! No Signal?

I have a Sony tv model No. KP-46WT510 ... I was watching it fine until suddenly the picture turned snowy and it said No signal. Yet the other 3 tv's in my house are working normally. I am able to watch DVD's on it fine, I just cant watch basic cable. Also when I press the remote to change channels up and down it doesnt change it stays stuck on 1 channel unless I press it manually. Could I have pressed something on the remote that blocked the signal? I have a philips universal remote. Help me anyone......? Thanks