Driving the car and all at once all my dash lights went out and now it will not start

Sounds like the charging system needs to be checked. Charge the battery at a slow rate for about two hours, then try to start the engine. You can start the testing by measuring the battery voltage with the engine running. It must be between 13.75 to 14.75 volts. If that is what you find, it is okay to have your mechanic perform the rest of the tests, but that requires a professional load tester.

GM generators starting with 1987 models have an extremely high failure rate. When you need to replace the generator, to reduce the number of repeat failures, always replace the battery at the same time unless it is less than about two years old. These generators develop a lot of harmful voltage spikes that can damage the internal voltage regulator and diodes, and interfere with computer sensor signals. The battery is the key component that dampens and absorbs those spikes, but it loses its ability to do that as it ages and the lead flakes off the plates.

Measure the battery voltage to at least one decimal place and tell me what you find.

I've been pouring over the wiring diagrams and I'm very disgusted to find that Cadillac did something that Ford was famous for. That is making the instrument cluster the most intelligent, (unnecessarily-complicated) computer on the vehicle. The wipers, radio, and starting systems are all computer-controlled, and that computer is the instrument cluster. This is not an area of my expertise except for what I read on other posts. My suspicion is the instrument cluster needs to be repaired, but before it is unplugged, your mechanic will check the 12 volt feeds and the ground circuits. If any of those are missing, the cluster will be dead or unable to perform some of its functions. I'm afraid this is likely to be a job for the dealer unless you have a good auto electrical shop nearby. The best you're going to be able to do yourself is check the fuses inside and under the hood.

I didn't really help with this problem, but I'm happy to hear it's solved. Come back and see me again.