Your keyboard has one or more keys that don't respond
Symptoms
- If your keys are not responding
- If the keys you've clicked do something different then what is pressed
- If keys are jammed or feel spongy
Solutions
Clean keys
- Blow or use compressed air to clear any debris under keys.
- Wipe keys with damp cloth.
- If keys are physically still feeling spongy or jammed, this may be a hardware issue. Contact support or your IT team for next steps.
Use the Keyboard Viewer to test whether the keyboard keys are responding correctly when they are pressed.
Choose Apple menu > System Preferences, then select Language & Region.
Click the Keyboard Preferences button.
Click on the Input Sources tab.
Make sure that the keyboard language that you use is listed on the left side. If it's not, click 
and choose from the languages that appear.
Select the checkbox next to Show Input menu in menu bar.
Click on the Keyboard tab, then select the checkbox next to Show keyboard and emoji viewers in menu bar.
Choose Show Keyboard Viewer from the Input menu 
in the menu bar. The Keyboard Viewer showing the keyboard layout appears on your display.
Type
the key on the keyboard that doesn’t respond and see if the
corresponding key highlights on the Keyboard Viewer. If it does, that
key is functioning correctly.
Check
to see if you have Mouse Keys enabled.
If you enable the Mouse Keys
feature, many keys might not respond as you expect. Here's how to turn
off Mouse Keys:
In
OS X 10.8 or later, choose Apple menu > System Preferences. Click on
Accessibility, then choose Mouse & Trackpad from the list on the
left side. Then deselect the Enable Mouse Keys checkbox.
-
In
OS X 10.7.5 or earlier, choose Apple menu > System Preferences.
Click on Universal Access, then select the Mouse & Trackpad tab.
Then select the Off button next to Mouse Keys.