Could you be a bit more specific on what happened. What "red oil light" came on? When you changed the oil, how much came out; was it near the 7 quarts that is supposed to be in the engine? Have you been checking the oil level regularly? Is the oil level sensor working? Now when you say "won't start" does that mean the engine rotates when the start button is pressed but the cylinders do not fire, or does it mean the starter is not rotating the engine at all? Really dumb question is, are you sure you have the clutch depresses (manual trans) or the brake pedal pressed (automatic trans) when you are starting it?
Kfrazie1 may be correct, the oil (pressure) switch may be bad. Try jumping the terminals and see if the motor will fire. Or it could be the brake boost system, early on, cars with automatics were having problems with the brake pedal being really hard and not allowing the safety-start switch to activate and allow the engine to start.