Hi, i have a sony

Make sure it is plugged into the back of the computer correctly and that it is in the right place. If that does not work, then turn off the computer by pressing the button on the keyboard that brings up the start menu and pressing the up arrow button and pressing enter. After it goes off, then unplug both the mouse and the keyboard from the computer and let it sit for a minute. Then plug both of them into the computer and turn it on. It should work then. If not, you might have install the drivers for the mouse in yourself either from a cd or from the internet.