I've recently erased my Hd (El Capitain was giving me issue) and I'm unable to log into the Mac app store or iTunes. Formatting downgraded me to Mountain Lion. I opened the App store to upgrade to Yosemite. No luck. Formatted HD again. No luck Managed to install Yosemite as my Brother has a Mac too. Installed Yosemite via a USB from my brother Mac, App store still comes up with the same error. I've called Apple but they don't know what it is, since apple.appleid.com works, my iCloud.com works. It's just the stores! My account has now been "disabled for security reasons". Resetting it doesn't work either; email isn't sent to second account and answering the security questions don't work - it doesn't accept the correct answers to my DOB and credit card Any ideas?