Can i make a pik i edited on photoshop 3 back to normal?

I designed a picture a few years ago with photoshop cs3 and I saves it as png and I wanted to kno if I can get the picture back to how it normaly was cause its the only picture I have and I want it bak to normal!! Btw I still have photoshop cs3 and how do I do it to make the picture back to normal if its possible.