I replaced the bulbs for the reverse lights and they are still not working?

Have you ground at the black wire at the back up lights and 12 volts at the red/black wire at the back up light sockets when the car is in Reverse key on engine not running? on a manual transmission look for a switch on the side of the transmission two wires red/black, white black, white black should have ignition supplied power from the 10 amp fuse in the fuse box. If it has power and the lights don't work disconnect the switch and put a paper clip across the switch if they now work the switch is bad. Switch colors are the same on an automatic but you have to do the same test at the inhibitor switch on the transmission.