How many miles are on this vehicle?
How has the battery been tested?
This very well can be a weak or shorted battery issue. Although the instrumentations and lamps illuminate, the engine starter may not have enough power to turn the engine. It requires the largest amount of power than any other component on the vehicle. The first item to check is the battery cables for being tight. GM had a issue with there side post style batteries, which the cables become slightly loose and will cause this same concern. If the cables are tight, try to have the battery charged and tested or jumped started. If the battery is internally sorted, it will not accept a jump start. One other item to check is be sure the "Security" or any other anti-theft lamp doesn't flash while your trying to crank the engine, this can mean the system has disabled the engine.