Mouse/Trackpad working but won't click.

Hi there,

So I have a Macbook Pro 13inch, non-retina, which I bought July 2013. When at home, I've got it hooked up to a Thunderbolt Display. Recentley, both the optical mouse I use through USB 2.0 port & the trackpad on the Macbook itself will scroll around, but refuse to actual click on something. I've read that this can be due to the battery reaching the end of it's life, but that's highly unlikely with the age of the laptop.

Has anyone got any advice/fixes?

I've checked all my device settings for the mouse etc. but it all seems pretty normal to me.

Thanks,

Jack