Foreign letters such as (à é è ç etc...) by pressing a key for a few seconds, not working after brand new 13 MacBook Pro is on for a few hours.

you can always hit the option key + letter to get the one you need.

Option + e (accent)

Option + u (umlaut)

Option + c (ç)

etc.

Check your input (system preferences > Keyboard > input sources)

The method you described, press and hold works for me on the same version of Mavericks.

Check your region settings, you can soft-reverse the keys/remap unused keys for the special characters.

You aren't saying what isn't working... What languages/characters are you trying to use?

Re-mapping the keyboard to the language you need/using unused keys for the characters is the best way to go about it if you use a certain symbol alot.

For reference:

http://support.apple.com/kb/HT4896

You can run this command in Terminal to restore press and hold functionality.

defaults write -g ApplePressAndHoldEnabled -bool true

(log out and back in to complete)

We kinda know that the press and hold isn't working for you.

I was saying that we aren't getting feedback about the suggestions I keep giving.

Are you attempting them? Do they work? Have you tried the key remapping yet?

This is like pulling teeth, it is very frustrating to continue to attempt to help.

On forums, they are a give-and-take. You have to work with users suggestions and comments and then acknowledge everything mentioned. We ask you to try X, Y, and Z methods, Please respond accordingly about X,Y,Z and don't worry about W unless something in the (xyz) methods changes the outcome of it.

Please answer about everything asked about, it will help me find a solution so much faster.

Things we need answers on:

Attempt to mapping unused keys to your preferred symbols

What character(s) from what language(s) are you using?

Have you considered changing the input language to the preferred?

What are all of the characters you want to make?

What is the frequency of use?

I tested the command, it works in Mavericks.

Did you copy everything inside the quotes? (but not the quotes themselves)

"defaults write -g ApplePressAndHoldEnabled -bool true"