Engine not turning over/starting
 

Its for my buddies truck. 94 Ranger xlt 4.0 4x4. Truck ran fine before. But he let it sit for a month, and now its not starting. He replaced the battery, starter and solenoid. Any ideas why its not even turning over? Its acting like it has no juice. Some guy at the store said the motor might have froze? Lol? Idk But any help is appreciated!

ps-checked the "big 3" but they seem fine