I’ve never fixed a floor jack but from what I see I’m not sure so I may be wrong but it looks like a hydraulic piston popped out cuz it barley has any pressure now but yeah I still really don’t know how to fix this
From what I can see you are missing a piece. Looks like the piston goes in the bore, with the spring on the outside and the cap on the top. Did you try to just stick the pieces back together?
Looks like the Chinese school girl broke from her shackles and made a break for it through the jack piston bore.
Seriously that's probably a sign that this is an unsafe piece of equipment. The tolerances on the moving parts have reached the point of spontaneous self-disasembly. Let it go.