Yes if a stain depending on the solvent (water or hydro-carbons), there may be some luck.
with the water solvent paint it does not generally soak in as much. If the other type of paint then it most likely soaked in and mm may need a lot of wood to be removed.
Fence just get the paint you want and try again. yes just sand it to get a key for the new paint on top.
At least you had a go and next time you will be able to do it yourself. By the way gloss finish looks really good (on floor) if the traffic is nice eg not many scratches and people not wearing shoes :-)
