2000 Ford Contour Rear defroster

It should be pretty obvious that you need to talk with someone from the shop that replaced the rear window. They deserve the chance to correct any mistake that was made. The mechanic might have forgotten to connect one of the electrical terminals to the new glass. He might have installed a window that doesn't have the heating grid. A fuse could have blown from a momentary short while a terminal was being disconnected. He may have purposely left the terminals disconnected for now to avoid moving the glass if there is an adhesive that has to set first. In that case he should have told you when to come back to have the wires connected. That only takes a minute or two.