I have both an internal and external keyboard but the key-repeat has stopped working. I've tried changing both 'Key Repeat' and 'Delay Until Repeat' as shown below but no setting seems to be helping.

This is a brand new mac (5 weeks old).
I have both an internal and external keyboard but the key-repeat has stopped working. I've tried changing both 'Key Repeat' and 'Delay Until Repeat' as shown below but no setting seems to be helping.

This is a brand new mac (5 weeks old).
Well it looks like there are a couple solutions:
Option 1. Enter this in terminal: defaults write -g ApplePressAndHoldEnabled -bool false. To disable repeating keys again, enter the same command except change the false to true.
Option 2. Download Mountain Tweaks (I assume you're on Mountain Lion, if not, download Lion Tweaks) and click the "Yes" option for "Enable Repeating Keys":

If running
defaults write -g ApplePressAndHoldEnabled -bool false
seems to have no effect, try a restart. This seems to be necessary in more recent versions of OS X.
By default, on macOS (since at least OS X Lion), when you hold down a key, it will display a popup allowing you pick a special character if there are any assigned to that particular key:

If a key doesn’t have any special characters behind it and you hold it down, nothing will happen.
As stated in Apple's docs:
You can add accent marks and special characters to some letters. For example, click and hold the a key to type à, á, â or other characters.
If you set the Key Repeat slider to Off, special characters won’t appear when you hold down a key.
Set how quickly a key repeats on Mac
To disable special characters popup and return traditional behaviour with key repeat, run following command in Terminal:
defaults write -g ApplePressAndHoldEnabled -bool false
Then restart applications (or computer) to update settings.
defaults write -g ApplePressAndHoldEnabled -bool false– pasawaya Aug 01 '12 at 07:59