App Store, Messages, Software Update not working on Mavericks

Question

Very recently probably the last couple of weeks, I've been unable to open the messages, App Store and most of the Utilites Apps on my Macbook, I'm on Mavericks. I can't even do a software update. Any ideas what I can do?

Answer 1

Try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work. The intent is to see if it is specific to one account or a system wide problem. This account can be deleted later.
Isolating an issue by using another user account
If the problem is still there, try booting into the Safe Mode using your normal account.  Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application un-installer. For each disable/delete, you will need to restart if you don't do them all at once.
Safe Mode
Safe Mode - About
If those don't work, do a backup. Boot to the Recovery Volume (command - R on a restart or hold down the option key during a restart and select Recovery Volume). Run Disk Utility Verify/Repair and Repair Permissions. Then reinstall the OS.
OS X Recovery
OS X Recovery (2)