First of all, you have to rule out whether your wireless mouse is the kind of dark, and recall that when you normally use a wireless mouse, there is no red or blue light at the bottom.
(Usually do not pay attention to then look down) If the light is usually bright, and now suddenly not bright, first check whether the switch at the bottom of the mouse is off (some wireless mice are not switched, connected to the battery means open).
If the switch switch has been turned on, but the light is still not on, then it is time to check the battery, open the battery cover of the wireless mouse, some battery cover at the bottom of the mouse, and some in the tail, carefully observe it can be opened.