App Store on mavericks 10.9.2 no longer works

Question

OK I updated to to Mavericks 10.9.2 last night and thats when the app store no longer worked. I have tried everything mentioned in other threads like restoring Mavericks and restoring from Time Machine etc,etc,etc and nothing works. Funning thing is its seems to be a problem only with Mavericks as no one running Lion is complaining about this issue. All other apps work fine. I logged in as a guest and managed to open the App Store and update itunes but I wont be able to do this with all my other programs because they dont exist when logged in as a guest.
Any ideas anyone? Any help would be greatly appreciated. Oh and lets keep this to just the App Store hey. I see alot of people with a similar issue but its with other programs not the App Store and the real issue gets lost. So only things that can help get the App Store working again please.
Thanks in advance.

Answer 1

Thanks everyone for their help. Firstly I would like to let you all know about the email I recieved from Apple support. I was extremely impressed at how quick the did get back to me. I thought I would have to wait like 48hrs or something. But it was literly only an hour. So that was good. I wish I could say the same about the content of the email and support they gave me If you can call it that! PLease read them email below.
Hi Adam,
Thank you for contacting iTunes Store Support. My name is Lea, your dedicated iTunes Store Advisor. I understand that you are having a problem on Mavericks. As much as I would like to help you but as an Advisor for the iTunes Store, I help customers with questions about buying and downloading content from the iTunes Store and managing their accounts.
Adam, at this point we are going beyond what we can troubleshoot over email however, the good news is we do have the ability to get someone on the phone to continue this issue for us. The best team to help you with this issue is the AppleCare Technical Support Team. They do have more resources available to handle cases such as yours and will do all that they can to help resolve the impending issue.
I have included the appropriate phone number below:
(61) 1-300-321-456
If you'd like to speak to someone directly, I just want to mention that we have started a new option for customers who require support such as yourself. You can also create a technical-support case via our website and arrange for an Apple technical support representative to call you. To do so, visit:
http://www.apple.com/support/expert
I hope this information has been helpful and you are able to find a resolution with Apple technical support, please let me know how the call goes, either way. I know I will be leaving you in great hands, Adam! Enjoy your day.
Sincerely,
Lea
iTunes Store/Mac App Store Customer Support
Well yes please! Oh how much will that cost? Well in order for us to help you, you will need to purchase 1 years support! Your so called free update is going to cost me, to fix a problem you created. Great!
Needless to say I did not go with option A. So I tried option B.
Thanks for nothing Apple!
I ended up doing a restore from Time Machine, again! Not from within Mavericks this time. I resterted my Mac and held down the command + R key after the chime. I then restored from time machine, one month ago. Unfortunetly this took about 3 hours but the result was success. My App Store.app now works again and everything is back to normal.
Thank goodness I had a time machine backup. I would love to know what would happen if there was no backup! I think a fresh install may have been the only solution.
Needless to say I will not be doing anymore updates for a while. I am now back on 10.9.1 and all is good in the world.
Thanks again ot everyone on this thread who tried to help. Your advise is extremely valuable.