First, turn on the headlights. Now, have someone watch them as you try to start the car; do they get dim? If so, the battery is in need of a charge; If not, you need to check your connections at the starter. You may have a bad starter, starter solenoid, or connection.
Starter is defective, or battery is weak.
Try getting a jump start. Could be a bad battery. If your battery is good, then you will need to get a new starter. It may be the Starter or the battery make be dead,
Dead battery? Loose or dirty battery cables? Bad starter solenoid? Bad starter? Neutral switch?
maybe ignitoin or ignition switch
what does it do
The starter or battery could be weak. The weakness will cause the starter to turn too slowly to start the truck.
check the cables
check the starter
Neutral switch?
Bad battery, or starter problem.
Engine seized? Weak battery? Loose or corroded battery cables? Bad starter? Bad starter solenoid?
try the starter relay.