HDMI port on Macbook Pro suddenly stopped working. How much is it to fix?

The only source of definitive information is an Apple store genius bar or an AASP. We are Apple users such as yourself.

You might look at iFixit.com and Powerbookmedic.com for prices, parts and instructions.

Ciao.

No one here can tell you what the prices are to repair things. We are just users such as yourself.

What makes you think your HDMI port is dead?

You can take it to a Genius Bar for a FREE diagnosis, make an appointment first.

http://www.apple.com/retail/geniusbar

Also check system preferences/Displays make sure that you have all the correct settings.

Check that the cable you are using is good.

Make sure the display you are connecting to is set correctly.

Check here:

http://support.apple.com/kb/ht1573

Try resettind SMC:

1. Shut down the computer.
2. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer.
   Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.

. RESET PRAM:

1. Shut down your Mac.
2. Locate the following keys on the keyboard: Option, Command (⌘), P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on your Mac.
4. Immediately press and hold the Option-Command-P-R keys. You must press this key combination before the gray screen appears. Continue holding the keys down until your Mac restarts, and you hear the startup sound for the second time.
5. Release the keys.