Left click is not working.

I'm really in a mess here with my computer. My computer has always been one really big problem. I've had so many issues in the past, but this is one of the worst.

The left clicker is broken. I'm getting around currently by clicking with the touchpad which is not sustainable for me.
Everything else is normal. I've tried going to the mouse options but it says it's working fine.

I have to click extremely hard to the point where my fingertips start to ache in order to get it to actually click.

The touchpad click is not reliable for me whatsoever. I really need a solution.
My computer is a Windows 7. Please, can anyone help me?