Hello Susan,
First of all put some WD40 on the winder, you will need an electric drill, put the chuck of the drill over the winder and tighten up hand tight, turn the drill on for just a short burst and that should free it off, put some more WD40 on the winder but don't flood it, turn the drill on again and all should be well, if the winder does not free off with the drill then it is well and truly seized and you will have to replace it.
Ken
drivewithken@blueyonder.co.uk, March 2008