My 50 inch panasonic viera tv seems like it is stuck in 480, my hd direct tv and blue ray will not work, but my wi will. can you help

This set will do 1080P. If your external devices are set properly the set should automatically switch to there mode. Try chaning which inputs you are using, trying one device at a time. Use HDMI for you Blu-Ray and either HDMI or component for your Direct TV. Chek your setting for putput on both of these to make sure of your highest quality video. 1080P on the Blu-Ray 720P on the Direct( yes 720p is higher than 1080i).
If this does not reslove try doing a reset on youset.
Press and hold volume down on your TV and the menu button on the remote. The set runs a self check then displays the results. when finished unplug the set for about 30 seconds. when you plug the set back in and turn it on it will come up in the original set up mode. youe will have to reprogram your input setting channel scan ect. so try the other things first. I hope this helps.