Runs good shifted good it sat for a few days and now the clutch won't disengage
Probably just stuck. Pull it around the yard a bit. Put it in high gear (3rd, I think) and SLOWLY pull it while working the clutch.
If you have a big plow like a bottom plow or subsoiler, pull it in neutral untill the clutch releases
Pulling a plow or other load like sfsracing said, except I think it will have to be in gear but with the clutch pedal down, and if it also has a hand clutch like my older WD, you'll want that lever forward too.