Wow problem I didn't play WoW for quite a while, now I have a problem, when I try to log in I get this message "failed to apply patch". What's the problem with WoW?

Permissions sets could have changed:

Follow these steps to set them –

1.) Click the Finder icon in the Dock
2.) Open the Applications folder
3.) Open Utilities folder
4.) Double click the Disk Utility application
5.) Select the hard drive WoW is installed on
6.) Select First Aid option
7.) Click on the Repair Disk Permissions

Looks like you need to update the game before you can log in

There is a repair utility that you can get here
http://us.blizzard.com/support/article.xml?articleId=21465

Repair Utility
We have a repair utility that can check your files and replace corrupted files as well. You can get the latest version available here. Note: The utility is currently only available for Windows systems.
Note: With the release of 1.8.0 the repair utility (repair.exe) can now be found in the main World of Warcraft game directory on your hard drive

The latest patches for WOW can be downloaded here

http://www.fileplanet.com/100462/0/section/Patches

Hope that fixes your problem