I accidentally deleted my "contacts" App on my iPhone. How can I get the app back?
Unless you have jailbroken your phone you can't delete the Contacts app. Most probably it's either in a folder or on a screen somewhere. To find it again
If you can't find it, you could always back up your phone (to save the current settings) and also take screen shots of the various screens I have set up. Then go to the settings app and Reset the home screen layout.
Worst case is you wait while you restore your backup if this doesn't return contacts to the first screen.
Are restrictions on? You may have accidentally blocked the Contacts app and consequently it's disappears from the home screen.
The other thing is you could have moved it accidentally - use Spotlight search (scroll left until you get a search box) and type in 'Contacts'.
Hope I could help!