Same thing happened to me. Check out this thread with lots of stories and advice:
Less than two months after getting a new TV, we were sitting watching NCIS and suddenly the picture went black, but audio was still heard. Got up to see what, and found a huge crack in the middle of the screen, ON THE INSIDE!!!. Went to the retailer where we bought it, they directed us to contact Samsung. A technician was dispatched who took pictures and confirmed the crack was on the inside, due to a damaged panel. Samsung will not repair or replace, as this is not covered under their warranty. I am livid!!!! Now what to do?