Welcome to the forum.
If these are Power Gear that have external springs that pull the legs up.
Extend them, spray the legs with WD40, silicon, hydraulic fluid, oil, grease, anything. The goal is to get some lubrication on the shafts.
Hit retract. They should come up. If not look at the control panel to make sure it didn't time out and shut off. If it shut off, just turn it back on and hit retract again.
If this doesn't work, use a shovel or long 2x4 and try to pry them up.