I have an '87 chevy cavalier RS, brand new battery, alternator, oil change, full tank of gas all within the last 2 weeks. It has been running great, driving around town, back and forth to work(~25 mile commute) etc. It was real smooth...

I purchased a new receiver so I could listen to cds/mp3s while riding around, which I installed a few days ago. Upon trying to start the car after everything was complete, it ALMOST started, for a second or two. The windshield wipers even moved a couple inches, then nothing..it sorta stalled out and will no longer do anything. The starter just turns and turns.

I can only assume it's coincidence, and the problem would've happened regardless, since I followed the instructions almost perfectly for the installation...except one part. I didn't remove the negative cable from the battery before disconnecting the stock receiver. Could this have ruined anything mechanically? >.>

Turn the key, the starter seems to be working fine, but it just won't fire. Give it a bit of gas, and nothing happens, though you can smell the gas in the air afterward. Checked voltage on the battery, and it's at 12v DC normally, 11.2 while turning the key..seems power isn't the issue. Checked all the fuses, and they seem to be fine.

Mind you, neither my brother nor myself are car savvy by any means, but he says it may be a throttle-body issue. When manually engaging the throttle arm, you can hear the butterfly valve flipping, but it's not synced with the release. I recently had some work done on it, due to an extremely high idle which turned out to be an imperfection in the gasket below the throttlebody.
A bad installation finally taking it's tole?

I'm willing to try anything..I'm 23 years old, and this is my first car. I don't even have my license yet, which I was planning to take the road test this week. What can I do?

replacing the radio isn't going to fry the computer, especially in an 87 so that has nothing to do with it, you can check the spark plugs they may be covered in gas so clean them up or get new ones...

If you put your foot down when you're cranking it should go into anti-flood mode where the fuel injectors turn off but everything else continues, you should probably see how the oil smells, if you smell gas in the air its probably in the oil now too so you should change it, then check your distributor wires and check the distributor cap, if nothing looks corroded or dirty then its fine otherwise clean it

if that doesn't work, get a noid light for your fuel injector from pep boys or whatever, you take the plug off your fuel injector and stick it on the light, use it to check and see how the injector is firing the light will flash when the injector would have fired, it should be a fairly slow steady flashing, if it stays on you have a bigger problem, since it smells like gas I'd assume its firing in some way so it probably wont stay off.

If the injector isn't firing correctly then it could be the throttle body gasket, the resulting vacuum leak could confuse the computer. after that it could be a sensor failure, start with the MAP and the IAC (Manifold Absolute Pressure and Idle Air Control) or even the computer itself

I hope that helps, these earlier throttle body's ether worked perfectly or screwed everything up and its not always easy to find the problem since there are almost no engine diagnostics or ways to adjust anything