If your mouse is still under warranty, then you could probably have it replaced or repaired by the service center or the store you got it from.

If not, then you would have to do it yourself. First, you must examine the cable and check if there are any loose wires or cuts that could possibly damage the inner wires. If you see that they are already out, then that would be a bigger problem. And you might have to get a new one so that you would have better experience with it.