This same exact thing happened to me when I had my tires done... they turned the thing back and forth trying to experiment with it and got it all tangled up. Took me a while to sort it out, but I earned my doctorate in Tire Winchology that night.
Hopefully you have a garage if you live near me, because it's cold wet and miserable out there. Put some work gloves on. Get a friend if you have one willing to help. You're going to get under the truck and have the friend crank it a little this way and a little that way while you pop the plastic cover off the winch and try to untangle it. Once you get under there, you'll see which way it's supposed to go, and what they did with it.
One of the tricks is that you'll need some weight on the tire holder platform otherwise it's just going to flop around on you. Maybe bungee-cord a brick to it or something. You'll figure it out.
I guarantee you they used a power tool to try to force it up, then it got stuck so they turned it the other way, then it got tangled, then they all shrugged said said "it was like that when you came in."
Get under there and take the white plastic cover off and send a pic of what you're seeing. Maybe I can walk you through it.
Edit: Just re-read your post. Start with the weight idea, or if you have a friend helping, use your hands to put a little tension on the cable as your friend cranks. Once you get it sorted out, lower it down again and glop grease on the cable and mechanism like it's whip cream on pumpkin pie. Raise it up again, then lower it and attach the tire and give it a few up-downs to spread the grease.
