If it's a hardware problem, then it may be one of these two.
Maybe something was pressed on the usb port, and caused stress to the usb port causing one of the pins to break loose, if you plug a usb device in and slowly wiggle it a bit, do you hear a connect/disconnect sound?
If so, it may be possible to fix it.
the other thing, is maybe something got got tilted, like the usb device wasn't in right and the 5v line went to ground, and may have popped a fuse, if that's the case, you'd have to replace the fuse.
either one would require soldering.
Otherwise, i don't know how else leaving a mouse plugged in would damage it, especially if it's just a dongle/receiver for a wireless mouse.