Q: The mouse problem

I have a macbook pro13" and my mouse on the loptop is acting up. When I try to move it, it moves slow or way too fast and I can't get anything done! I've had this problem before and I kept clicking on the spot where green light is and the green light turned on and the mouse was working properly. Now I have the same problem and I tried the same old technique and it's not working! The light is not turning on. I can't look it up on google b/c it's giving me no answers. Can anyone help?