I checked the carb. When I loosened the nuts connecting the throttle cable to the carb, the carb was able to move and rotate freely. Also, I was getting movement in the cable when I disassembled part of it near the throttle handle under the instrument panel. When pulling the throttle, there was tension and movement. But when I try to pull the throttle cable with a pair of needle nose pliers, pulling on the small exposed part from the carb's end, it would not budge.
It has happened in really cold weather (below 28 Fahrenheit) before that I was not able to start the scooter because the throttle cable froze in the closed position. I am thinking that perhaps this time it froze in the open position while I was riding. I will tell you, it is not the most joyous feeling in the world when you first realize your ride will not slow down.
Thus, I believe that the cable is just frozen somewhere between the throttle and the carb. I put the vehicle in a garage, but it is not too warm. Here in Michigan right now, it is about 20 degrees Fahrenheit where I am. Perhaps I should just replace the whole cable, (using the good advice of my Haynes Scooter Manual I have in my dorm) and hopefully avoid future freezings like this. I will be going to get the bike later tonight, so I will let you know if warming it up gives any results. Thanks for the help, and no I will not stop riding in the freezing cold, so long as my bike still runs.
Tank Urban Sporty - 50cc.