Is it in skeins? Is it plyed?
If it is in single ply skeins, what I do is weigh a grocery bag down with a soup can, leave the yarn to soak in water for at least an hour, and then hang it up over a coat hanger and weight the skein down to dry.
If it is plyed and doing that then someone did a poor job of spinning. You can still try the same technique and see if it rights itself. It really depends on how overspun it is.
If all else fails put it in the buy/sell forum and let someone with a wheel buy it. If you have a wheel those things are generally easy, with a bit of time spent, to fix.
Good luck to ya. Let us know how it goes.