Mouse works fine - except when the electricity generator gets switched on (because of power failure), the mouse stops working.

A power failure event, and/or the generator coming on, going off, can produce power spikes or surges that can damage anything on your computer or connected to it. If you plug your computer, if applicable, and everything connected to it that connects to AC, and the cable that connects you to the internet, into a device or devices that protects against power spikes and surges, it's a lot less likely your computer etc. will be damaged by that. If it was a lightning strike that caused the power failure that can do even more damage, even if you do connect to such devices. The only sure protection from that is to unplug everything that connects to AC. If the mouse no longer works now, try the mouse on another computer, and try another mouse on your computer. If it's a USB mouse, try other USB devices.