Chances are, it is not your keyboard that's broken. Maybe Gmail keyboard shortcuts are turned off for your account. Fortunately, turning them on is easy.
Enable the Gmail Keyboard Shortcuts
To turn on Gmail's keyboard shortcuts in your account:
- Click the Settings gear in your Gmail's toolbar.
- Select Settings from the menu that appears
- Go to the General tab.
- Make sure Keyboard shortcuts on is selected under Keyboard shortcuts:.
- Click Save Changes (if you made any).
If keyboard shortcuts still seem not to work, try clicking somewhere in Gmail to make sure it has the input focus.
(Updated April 2013)