Windows PC start menu will not diisplay

It has been this way several days now. If I left click on the Start menu icon (lower left corner of screen) nothing happens! To shut down the PC, I must right click on the icon and select "Shut down and sign out". I have no access to the start menu programs. The only ones I can get to are on the Task Bar. I rely heavily on the mouse to run programs due to some neurological issues that make actually typing something onerous.