On the way to work this morning I heard a whinning sound. Pulled over and looked under the truck and did not see anything. Drove all the way to work and back home. Went to back out of the drivway and the truck will not go into reverse.

Any reply will be appreciated !

year, engine, 2wd or 4wd

welcome to AF. If the fluid is clean and full the trans will have to come out as the reverse hub is stripped. As mentioned, in the future you must post the year and model.