Zoom in and zoom out shortcuts don't work anymore
Hi, I accidentally restart my my macbook and my keyboard shortcuts (command -) and (command =) suddenly doesn't work anymore, I tried to zoom in and zoom out while using keyboard shortcuts (command -) and (command =) on firefox, preview,adobe reader, safari and chrome, but none of these apps works.
Please help!
MacBook Pro, OS X Yosemite (10.10.5)