no gas ?
To fix your shock:
Unscrew the brass fitting slowly of the lower shock end......this will let out the nitrogen gas.
Put shock in a vise held by the lower eye.
Use propane torch and or heat gun to carefully heat the area of the shock body where the aluminum nut screws into the body holding the shock rod.
1" wrench or big cresecnt wrench unscrew the aluminum nut where the rod comes out. Now if you are lucky, this nut comes out and the body of the shcok does not unscrew from the lower shock end.
If nut comes out your good, put eye end of shock rod in vise, unscrew nut holding piston, without scattering the parts all over the shop set this aside, wrap old inner tube around shock shaft held in vise, head eye end to loosen locktite,unscrew eye. Screw eye onto new rod, slide alum nut/wiper assembly on, set piston back on just the way you took it off. Put shock body in vise, fill 2/3 with shock oil, ( don't have any use automatic transmission oil ), reinstall brass plug in bottom of shock end, compress piston ring slide valve into body and slowly move it back and forth in oil to bleed out bubbles.add oil and gently stroke piston, work piston up to shock threads covered with oil, add oil hafl way up threads, screw in aluminum nut, take brass plug out of bottom of shock body and go to hydraulics shop and buy scrader valve stem to fit, scew into shock body and put all the air your compresser has in there.
Shock will work fine to ride and get you back on trail, perfect? maybe not? but when season is over send to shock rebuilder to have it reassembled with nitrogen and floating piston dept set correctly.
Air instead of nitrogen won't hurt a thing, nitrogen better, but air better than sitting and watching, the key to putting air in is replacing filler rubber/brass pellet set up with regular valve stem ( schrader valve ), then air pump, compressor, bicycle pump any thing will work, even it you don't put any air in the shock, you can ride, kinda soft for most, but won't hurt anything.