If it's the door switches, you can very carefully disassemble them, clean the internal sliding contacts, and resassemble (using plenty of synthetic grease or vaseline).

When you carefully pull out the switch from the doorjamb, the attached wire will be tight. Unplug the wire from the switch and then attach a leash to the wire. If the wire falls back into the jamb, you'll have a project retrieving it.

I find it unlikely that all four switches failed the same way at the same time.

Check the connections at the dome light fixture.

Also, you can run an experiment by carefully pulling out one switch and grounding the wire manually. If the dome light works, then the switch or its ground connection needs attention. If the dome light does not work, then it's a problem with wiring or the dome light itself.

Keep in mind that the driver's door switch has two connections -- one for the key warning chime and the other for the delayed dome light (via a relay). Only the driver's door goes through the relay -- all other door switches connect directly to the light.
--
Don Foster (near Cape Cod, MA)