My 42" LG plasma tv suddenly went very dark and seemingly completely black around the edges. Any suggestions? I have tried unplugging it and switching inputs, but to no avail.

Http://www.scribd.com/doc/7580885/LG-TV-Plasma-Training-Manual

http://elektrotanya.com/lg_42pc3d-series.pdf/download.html
Please download these two manual, these are what are used to train the engineers to repair these units, inside are troubleshooting and repair procedures, follows these and you should get an insight as to what is going on. Now if you feel that it you do not want to do it. It is my professional advice that you, get you set looked at by a LG, Authorised Service Centre, contact an LG head or local office, and ask for a referral to an Authorised service center.and then contact them, and ask for free "Quote", this way, you will be able to make an informed judgment, as to repair or replace. As these days seemingly insignificant SYMPTOMS, often cost as much to repair as it may cost to buy.