Hi, first if able to use a breaker bar or ratchet with a 18mm socket to try and turn the engine clock wise by hand at the front of the crank. If engine turns, the engine is not the problem, and likely just have a bad starter. Another good trick to see if the starter is going bad is have an assistant hold the key in the start position, and hold it there, while you hit the starter with a hammer, if engine cranks, the motor of the starter is bad. Block the wheels, have the parking brake on and make sure the truck is in park when doing this. Starter is located on the rear passenger side of the transmission, where the engine meets the transmission.
Next, if still no luck, remove the battery and take it to an auto parts store to have tested, could just be a bad battery, even if replaced recently, if battery prooves to be good, I would remove the starter and have a parts store or shop bench test it. Will likely be a bad starter or battery.