Hello and welcome to the forum!

First, do you mean the icon shown in the pic below (from my iPad's Home screen)? Second, please provide the model of your granddaughter's iPad and the iOS installed. Finally, have you tried to 'Reset' the iPad? If not, hold down both the HOME & ON-OFF buttons until the Apple logo appears, release, and allow the device to reboot - see if the icon reappears. Good luck - Dave
P.S. if still an issue, then google "ios settings icon has disappeared" and look at some hits.
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