On my coach the HWH system pump has four valves on top, each with a handle. Turning the handle will release the pressure causing the jacks to retract. I don't know if my 1993 system is the same as yours.
As others have suggested, you have to start the engine and "air up" the suspension to raise the chassis up and allow the jacks to swing up, if you have that type of system. Also driving forward can force the jacks to swing up, but again only if you have that type of jack system. If they don't swing up, you'll cause quite a bit of damage driving forward while they are still down.