truck starts but stuck in park

There are several thing here you need to check, first being the shift lock .does the truck need to have the brake depressed to put the truck in gear if so then this may need to be realigned .if there is no lock then check the linkage in the column and under the truck where the linkage meets the transmission if anything is bent this can inpeed the shift. If it is a cable linkage the cable may be frayed and this can stop the shifting .There is also the column shift lock that is operated by the key . If the lock cylinder is not functioning properly this may not be getting released when the ignition is turned. Hope one of these Ideas helps