You can't delete the camera. It is a piece of hardware. You can, however, mess with the app. Also, you can always use the button on the phone for the camera to access it.
First check to see if it is just the app was removed from the home screen. It happens. Tap and hold anywhere on the empty background of the home screen. You should then get a screen with icons, widgets, etc. Look for the camera icon there. If it is still there, then just put it back on the home screen.
Now if there is no icon for it, which would be rather odd since it is an app that should not be able to be deleted from the phone, then you may have no choice but to do a hard reset to get the app back. If that is the case, be sure you back up ALL personal info first...