Unknown update account address

[ManUMark]

So, i live in Thailand and got my iPad from a grey import shop as the offical roll out is delayed. The purchase price included some Apps that the shop had brought and offer as a sweetner. I had a iStore account from before and changed the default over to my account and now i seem to have a problem. On updating Apps that i have purchased and free ones thru MY account i get diverted to an unknown account name?
No 'serves you right' replies please as most of the preloaded Apps were deleted long ago.

 

[JMG]

Check through iTunes to make sure your account is still valid. If so, then try resetting your settings in settings. If that doesn't work then you might have to resort to a restore.