Before you locate a lost Iphone on silent ,make sure that you had turned on “FIND MY IPHONE” in your phone’s settings. If yes , then follow the below steps
1) Go to http://www.icloud.com on your browser and sign in to your account .
2) Now click on FIND MY PHONE icon
3)Click on ALL DEVICES in the center top and select your lost device which you want to find.
4)Now click on PLAY SOUND button. That’s it
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