cant access my application store for ipad 4

What happens when you try to access it, and have you tried any of the following to fix it :

- closing the App Store via the phone's taskbar (double-click the home button to open the taskbar, then press and hold an app on there until they start to shake, then press the ➖ to close an app)

- logging out and back into your account on the phone via Settings > iTunes & App Stores

- a soft-reset (i.e. reboot) by pressing and holding both the home and sleep buttons for 10 to 15 seconds until the Apple logo appears

i tried but still the same issue.

can not connect to app store. and blank

sometimes it is just blank. only thing working is the updates.

same for ibooks too.

and if i delete the app store than how will i get it back?

You cannot delete the App Store app, it's built-in to iOS.

As well as doing what I suggested above, you've also tried resetting your network connections (Settings > General > Reset > Reset Network Settings) and then reconnecting to it (you will need to re-enter your network's password) - and does it work on other networks (e.g. friend's) ?