The belt squeels because it is either loose or glazed, if it's been doing this often then I would say it is probably glazed and should be replaced. When replacing the belt you may also want to replace the automatic tensioner. If it is not putting enough tension on the belt it will be slightly loose, which will cause the new belt to squeel and then become glazed.
Belt dressing (in aerosol can) will silence the belt, but that is a temporary fix at best.
The best thing you can do is just replace the belt and tensioner if needed.