Open up that egg thingy (regulator) and see if you just blew a fuse.
If not then you will need to get a replacement for the egg OR you could run the screen directly off the 12v line in your carpc. You dont need to use the same wire but make sure you replace it with another wire the same gauge (thickness) or thicker.
EDIT: get a few opinions before hooking the screen up to the 12v line without a fuse. I dont want to be responsible for a broken screen