1998 Mitsubishi Eclipse airbg deployed

The two things are not related. For the air bags, for liability reasons, you're supposed to replace all of the crash sensors. There is a "safing" senor inside the computer module and there may be two crash sensors at the front corners of the car. We replace them because when the safing sensor and either of the front sensors activate, there is typically going to be a tiny arced spot on the contacts, and in another future crash, the moving contact could hit that same arced spot and fail to make a solid connection. That can lead to a lawsuit involving anyone who worked on the system in the past.

On many car models you need a scanner to read the diagnostic fault codes, then erase them. There may be no other way to turn the warning light off.

For the no-crank, what are the symptoms? Do you hear a loud clunk from the starter solenoid? Do you hear a light click from the starter relay, if there is one? What happens to the brightness of the head lights or interior lights before and during trying to crank the engine?

To add to Doc's answer.

The Airbag module is "One time use" and acts as a black box like in an airliner. It has to be replaced whenever a bag is deployed.