Window 10 - Left mouse won't click on taskbar?

After the untimely death of my laptop, I purchase a new one and downloaded the free upgrade to Windows 10. All was fine for a couple of weeks. Then the left mouse button stopped working when trying to click on the task bar. This makes it impossible for me to launch programs, adjust volume, search.....well, it prevents me from doing almost anything. If I didn't happen to have a shortcut button on the desktop for the internet, I couldn't even be here.

I've searched the internet for help. I can see others have this problem. But, haven't found any instructions on how to fix the problem. My computer is almost useless. I need it for work and pleasure. Please tell me what how to fix. Or if it isn't fixable, how do I uninstall Windows 10. I believe the laptop came with Windows 8 installed. But, I'm not certain.