How can I update my rooted phone?

[AC Question]

My device is running Android 4.4.2 which is strange because I saw somewhere that the current version available is 5.something. When I tried to system update an error message came up saying "The operating system on your device has been modified in an unauthorised way. Try downloading software updates using Samsung Kies on your PC or visit a customer servive centre."
So I tried using Samsung Kies but it wouldn't work so I emailed Samsung explaining my situation snd ended up giving them my ODIN details. They told me my device has been rooted and my warranty is now voided so they can't help me.
Can anyone tell me if theres a way of updating my device or how to unroot my device and then update? (Btw if you're going to be really technical can you explain it thoroughly)
Many thanks,
Person stuck on Android 4.4.2

 

[H3aTeRzz]

Carrier?

 

[divergentdavin]

Samsung Galaxy S4 Mini....or do you mean my phone network? in that case o2.
(I just made an account btw this is OP or whatever you call it haha)

 

[H3aTeRzz]

K. I'm not familiar with O2, but my suggestion would be that you find the OEM software from Sammobile and use Odin to reflash it. You might want to see if someone here is familiar with O2, cuz these flashes vary from carrier to carrier. Good luck.

 

[Rukbat]

The flashing is the same - see [Samsung] How to flash Stock ROM via ODIN. Just make sure you're flashing O2 firmware. (And back everything up first - see Backing up an Android Device - because flashing a ROM gives you an out-of-the-box phone. All your apps, data and files will be gone and you'll have to restore them.)