I had the same problem. Fortunately mine is under warranty. However before I sent it in for service. I pounded on the left click button pretty firmly and it started working again.
Give it a try. Thanks.
I have an Acer Aspire V3-731 laptop running Windows 8.1 64-bit.
Yesterday the left and right mouse button stopped working (i.e I'm not able to select Excel cells or buttons in other programs in the lower right hand corner of the screen (roughly 3"x3"). I first noticed the problem after I plugged into an HDMI cable to use the display of a large-screen tv for a presentation.