The valve is internal, At the bottom of the chrome rod you see sticking out the top. Try raising the forks all the way up & lowering as far down as they'll go multiple times. Sometimes it'll free up the valve. If it refuses to lower all the way after repeated raising/lowering , the cylinder is going to have to be removed & taken go a hydraulic shop.

I just reread your last post- you replaced the hose to the cylinder that's stuck halfway up? How did you support the carriage when you removed the hose?