all bottom icons are missing

None of those apps can be deleted. They are on your iPad somewhere. Swipe from screen to screen to look for them. Do a search - swipe to the right from your first home screen to get to the Spotlight search. Some of the apps can be hidden in restrictions - check Settings>General>Restrictions.

If all else fails - you can reset the home screen layout. Settings>General>Resets>Reset home screen layout.

Icons on the bottom bar can be moved to other locations. Other icons can be moved to the bottom bar. The bar itself cannot be deleted by you can customize which apps reside there.