It's unlikely it will ever be worth anything considering the damage but I'd at least find out more about the coin first. Start with a good peroxide bath. Next would be electrolysis. Any time you get it to a point where you can tell type, date, and mint mark, look it up to see if has any value before continuing. If it's just basic 90% silver with no collector value, go ahead and tumble it if you want. Depending on value, it might be better not to do too much cleaning. That's kind of a judgement call depending on if you're going to try to sell it or just put it in a coin folder. Either way you go, I'd also straighten it. I like to use two pieces of hardwood, like oak, to sandwich the coin in a vice and take the majority of the bend out. Then, on a relatively soft surface (I use a piece of aluminum plate), tap out the rest of the bend(s) with a hardwood dowel or scrap piece of wood. No vice? Lay the coin flat on a piece of plywood, cover the coin with another piece (making a coin sandwich), and smack it good with a big hammer. Repeat as necessary to get the coin as flat as possible. Some damage might never come out so don't think you can make it perfect.
