I accidently pressed the channel button on my remote instead of the volume button. I now have no picture or sound. I tried returning to the previous channel but it keeps saying " channel not available". How do I fix this?

Not familiar with your model, but the problem sounds generic. I am guessing your set is hooked to a cable tv box, and that is where you need to change channels. I also guess that when you changed channels on your TV you probably moved from channel 3 to either channel 2 or 4 and the cable tv box is not sending to those channels so you lose picture and sound. Now, more guessing, you try to put the channel back to 3 on your TV, but still nothing happens. OK, if close so far, there are a couple of things to try. First, be really sure you are actually going back to the same channel you started with. Assuming you don't actually have the signal coming in on an auxiliary line-in and that you had it coming in on a channel, you may need to reset the presets on the television so that it recognizes the one important channel the cable tv box is sending out -- just follow your television menu to select or set channels. There is one more possible easy problem ... I have seen this one happen, after getting the channel correct and reset, if it still doesn't work, you mght need to turn the set off and wait one minute, then turn it back on WHILE the cable box is ON. This can cause the set to RE-Latch onto the cable box signal. It really doesn't sound like something is truly broken or needs replacement, sounds more like a user error. If your set is still under warranty, just call the Panasonic hotline (find it in Google, and they may be able to walk you through exact instructions for your model). Hope this helps.