Why doesn't my iPhone 5 have personal hotspot?

Personal hotspot has disappeared. It's not there when I open Settings.
It's not in Settings<General<Cellular either. My carrier doesn't require paying for tethering to work and everything about my iPhone is identical to my friends iPhone. All the settings, iOS versions, all that stuff.
Why doesn't my iPhone have personal hotspot? It just doesn't appear and, apparently, nobody else has had this problem, because when I search on Google it doesn't appear. Everyone says "Settings<General<Cellular" but it just isn't there. It just says "Cellular network settings" which takes me to the APN where the DATA settings of my carrier are included. No signs of "Personal hotspot" anywhere. Why is that?

Added (1). Oh dear… First answer to my question and it's already the same thing…
I clearly stated that "SETTINGS<GENERAL<CELLULAR" does NOT have Personal Hotspot there on my iPhone.
I would appreciate people taking the time to actually read what the problem is before answering…

Added (2). 6.1.4, the latest firmware that is only available on iPhone 5.
Certificate? I will attempt that.

Added (3). I can't find "Profile" in General. IPhone 5, iOS 6.1.4.

Settings/General/Cellular

Is it updated to the newest firmware? If not, there's the problem. Also, maybe your friends have different carriers. I know my Aunt's iPhone 4 has a different setup from mine. Try searching Google with your phone, carrier and hotspot.

I had a similar issue with my iPhone 4. Turned out there was a certificate installed which interfered with the hotspot. Try this and let me know if it works.

Setting - general - profile. Then remove the certificate.

Edit: Ah, sorry bud - at least I tried.

You carrier could have removed the option to do so as was the case for mine back in 2010. Not all carriers support it for whatever reason despite the phone being fully capable of doing so.