How do I get my photo icon back?

You can't delete the preinstalled apps. It's impossible. Look for the app on other screens, swipe from screen to screen, look in folders.

You can also reset the home screen layout and the icon will reappear - but the home screen will return to the way that it looked when you first activated your iPad.

Settings>General>Reset>Reset Home Screen Layout.

You can't delete the Photo App!

Try this; Keep the Powerbutton and the Homebutton pressed at the same time until you see the Apple logo on your iPad screen.