First check the fuse, then check the bulbs, then check the switch.
There is probably a reverse light switch on the transaxle that is bad or unplugged
what to do if my reverse lights on my 1993 gmc 1500 truck wont work
Most likely the reverse lights were attached to the light bar.
Check your fuses
head lights won't work, no power to them, signal works , reverse lights work
Try bypassing the reverse light switch that plugs into the transmission. If your reverse lights come on, voila! Problem solved. Buy a new switch.
The problem is the reverse light switch. It is located on the top of the transmission that should sloved your problem.
brake switch
Sounds like a Ford! Brake and reverse light not functioning will keep vehicle from leaving Park!
the reverse light switch is either out of adjustment. or broken. new one should be fairly cheap
Replace the bulb first, if this does not work try the reverse switch.
broken circit in your light switch