Vehicle will not move forward, is it the transmission or could it be something else?

I was driving along and "Pop!!" then rough sputtering, and I knew the lovely Triton had spit out another spark plug (3rd or 4th time it has done that). Towed it to a nearby friend's house and parked it. Next morning, I re-threaded the hole, replaced the coil pack and plug, and was on my way down the road to work. At a stop light, when I stepped on the gas to go, the transmission seemed to slip a little. The more I drove the more it was slipping. I stopped, checked the transmission fluid. it was a little low, so I added a little fluid. I put it into drive, and it would not move forward. Tried switching it into 4WD low and high wouldn't move forward, same when I took it out of 4wd. It would only go backward, so I had to drive it in reverse around my apartment parking lot and finally got it parked in my very narrow garage (took a lot of pushing forward then driving in reverse and repeat). I had not had any problem with the transmission before this.

Could it be something other than the transmission? Maybe I knocked some wires to the MAF or TPS or some other sensor loose that directly affects the TCM? I just cannot afford to replace the tranny right now and I desperately need a vehicle for work. I am hoping and praying that it might be something other than the transmission itself. What should I check?? Also, on the gear shifter inside, someone broke off the tip and I had to rig the O/D button wires and attached the tip back on the shift lever with electrical tape. Could that be contributing to the problem?? No check engine light on.