First thing I'd do is crawl under the dashboard and check all connections are tight and in place. The camera draws such little power, I doubt a fuse blew. Does your camera come on when you put the transmission in reverse? That could be another place for the signal to fail. Also, make sure the display is turned on and contrast turned up.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI