How do i fix a broken mouse?

USAFRet

Titan
Moderator
Depends what is 'broken'.

What does it not do?

Make/model?
Reinstall driver, if necessary
If it simply doesn't click properly (very common) then the microswitch under the left button may be failing. You can maybe replace it, but it is almost certainly just easier to replace the whole mouse.
Mice go bad. Replace.