Did something happen with the keys lately? It would seem that the chip in the key isn't being read by the truck, so it thinks it's not a valid key and won't start.
Unfortunately, heading to the dealer, in this case towing it, might be the only option. The passlock computer in the truck could be bad and need replacement. That would then require the old keys to be reprogrammed into the system so it knows they are valid.
Doesn't sound like a cheap repair. Let us know what happens.