Blowsand, ok where did the fluid go, it could be water in the system as stated above, but if you suspect a leak, look at your rear drums and see if you see any residue of fluid leaking out from between the drum and backing plate. It will be very noticable. If so It is most likley your brake cylinder seals have failed, they have rubber orings/bushing that keep them sealed. Also check your front calipers for any leakage, along with the master cylinder and hoses/piping. If you have no leakage, then you should or have the system blead/flush this will remove all the old fluid and replace it with new. If thats all you need a shop will most likly do it for under a 100.00. only takes about 20 min if the guy knows what he is doing. If it is the seals, I woulld recommend having them replaced. Again, not a hard job, but most shops want to stick it to you. The replacement cylinders should be around 50.00 per axle at napa, plus what ever the shop charges for labor. Just buy them and take them with you or the rebuild kits for around 20.00 should be a last resort to rebuild them, lot of pitting ect....
As for as your op, yes turn the wheel. Hope this helps you out.
George & Julie
06 Diplomat PDQ