Yah I agree with 1 day if it's a roller ball there are these slits in the bottom there should be 4 indents two inside of the circle and two outside, line them up till there are only two and that opens the bottom. It's basically the size of one of those super bouncy balls you'd get from those machines. Make sure to blow inside the compartment it can collect a TON of dust and gunk and clean the ball as 1 day said. And I did think you were talking about a REAL mouse! If all else fails I say slam it on your desk a couple times that usually works wonders for me! Good luck! (sorry, I'm a computer geek)