I had something similar happen to me and my 1993 F250. I had let the truck sit for several days and it was real cold out (Around 0F). when I got in to it to go to a Fire call and could not shift or stop with out shutting the truck down. so I just ground gears until I got to the Fire House then Just shut down the truck. After I got back to the Fire house I started to check it out and found that my master cylinder was shot. I replaced the master and bled the air out. it worked fine for a couple of days then get real cold again and I had more issues. so I bled it again but this time i put a whole bottle of brake fluid through it and it has been working great since.

My suggestion is to check the Resivor for the clutch Make sure you have fluid, Bleed the clutch and try again.