1999 Chevrolet Suburban won't start

First of all, listen if the fuel pump runs for 2 seconds when you first turn the key to run. If it doesn't check the fuel pump fuse and the fuel pump relay. If the fuel pump does run, check the fuel injector fuse and see if the engine will start for a few seconds after spraying starter fluid into the throttle body.

Try another key first it may be the security system then dry out plugs with a propane torch check fuel pressure with a gauge shold be 60-66 psi with key on not running. If no diode in key try resetting security system.