My Epson did this to me recently and I thought for awhile it was the bulb. I fiddled with the cords and replugged it all in and it worked - I think the cord between the base and the top had come just very slightly loose. If yours has a bulb in the lid just for negs, it might have blown, too. Mine isn't user-serviceable; maybe you're more lucky.
Ditto what Bethe said. Check the cable that goes to the top/lid of the scanner. That happened to me as well. It drove me bonkers for days before I decided to check the cable and push it in/tight again - it came loose but appeared to be in place.