Is it on a steep slope in your driveway? Sometimes that will put a load on the Park gear and make it difficult to pull out of Park. You might try gently pushing the truck uphill (with another vehicle) to take some of the load off, which will usually then allow you to pull it out of Park.
But maybe I'm getting ahead of myself... First let me ask, is it even in Park? When you turn the key to ON (without starting it), what does the PRND2L display show? Will the truck roll at all?