I have a 99 Country Coach so I don't know what conversion you have but from your description of the button pushed I assume you have a CC. My guess is when you disconnected the grab bar light you broke the circuit to the isle lights. Meaning they are wired together in a series. You can probably tie the wires back together to complete the circuit and the isle lights will probably start working again. (Verify polarity on the wires if you can before reconnecting them.) If they still won't come on after reconnecting the wires, ck the control cards in the first bay in the ECC cabinet to make sure you have not blown the fuse. ( The electronic control cabinet)

The fuses are automotive type blade fuses and should be 10 or 20 AMPs. They will be marked as to amperage and they are referd to as ATC type fuses.