I want to restore some of my app like gmail

On you tablet you going to go to settings then hit the general tab. Once there go to application manager and hit the app you if you want to restore to factory settings then hit the clear data button on which ever app you want to restore and this is where you turn apps back on to but this time you swipe until you see turned off under the application manager and hit the apps you want to enable again by tapping the app and once you do you will see force stop on the left and turn on the right. Hit the turn on button then you should be good to go.