This is a simple solution based on an issue most commonly found on Windows 7 Operating Systems.
Common Solution: Simply hold down the shift key then release it after a couple of seconds to see if the key was stuck. In most cases simply pressing the shift key again resolves this.
Alternative Solution: Verify Sticky Keys is not active
To turn off Sticky Keys press the Shift key 5 times. Or uncheck the ”Turn on Sticky Key’s option” found under the Control Panel’s Ease of Access settings.