Mouse won't move curser.

sixfive

Have you tried unplugging and replugging the mouse. If it's a USB mouse that will get it going again.
I had the same problem, sometimes had to unplug-plug the mouse every few minutes. Very vexing. Eventually worked out that the mouse cable had a tiny patch that was badly worn just where it comes out of the mouse, if it pressed against the mouse then my screen cursor would freeze. I repositioned the mouse so that doesn't happen and it's been fine since then.

savemoney

Some mouse like the ms have a receiver with a button on the top to sync with mouse. Mouse has a button underneath

Rock_Bottom

Belnahua

On a more serious note, you've all missed the key point here.

The mouse is stuck in the task bar, that usually means an application has hung and won't return the desktop to user control. Although it's usually the other way around and the mouse won't enter the taskbar area!

I would try CTRL-ALT-DEL and get the task manager up and see if an application has stopped responding?