Q: How to retrieve personal hotspot in iphone 4s

Hello there padilla.carmel,

It sounds like you are unable to see Personal Hotspot in Settings like you used to. I would first quit the Settings app and restart the phone:

Force an app to close in iOS

1. Press the Home button two times quickly. You'll see small previews of your recently used apps.
2. Swipe left to find the app you want to close.
3. Swipe up on the app's preview to close it.

 
When you have done that restart the device and test the issue again:

iOS: Turning off and on (restarting) and resetting
 

I would next check for a carrier settings update if it still hasn't appeared:

iOS: Updating your carrier settings - Apple Support

If it is still not here, you should check with your Carrier to make sure that this function is still part of your cellular data plan according to this article:

1. Contact your carrier to make sure that they support Personal Hotspot, and that it's turned on for your wireless plan.

From: Get help with Personal Hotspot in iOS - Apple Support

If after all this it still isn't showing as an option, then I would next backup you phone to iTunes, then restore it as new and verify that Personal Hotspot is available again: 
 
How to erase your iOS device and then set it up as a new device or restore it from backups

If it does, then restore your backup to either verify it still works and the software just needed reinstalled, or isolate the issue to the backup file itself. 

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