stripped screw

I have a 2005 zx6r with 33,000 miles on it. I'm currently unable to ride it because when I drained the coolant and screwed one of the drain bolts back in, I believe that I overtightened it, and now it won't screw in right, and it leaks a little bit. (I'm talking about where you drain the coolant...

this screw is totally stripped...and its in there extremely tight..i tried using an extracting set but i think a little piece of the extracting bit brok and all of my drill bits keep breaking.. ive tried everything please help!?