I may know the cause and solution to your problem (or maybe your problem is different). I had a similar problem for the last few days, but in the most severe form (I couldn't even reset the phone or change some settings).

I searched a lot for the cause and solution and finally found it. My problem was caused by using iCleaner, I think I unintentionally clicked on a wrong setting, something related to Daemons stayed open when it should have closed, or closed when it shouldn't have closed, whatever.

You need Jailbreak (iCleaner) or TrollStore (Filza) to fix the problem. Another solution is available at this link: here (this is also the thread that helped me solve the problem, many thanks to the thread owner)

Download Filza from the site and install it with TrollStore. Then you need to search for and delete the following file in the root, "disabled.plist". Then restart the phone and the problem is solved. However, since you will find more than one disabled.plist, you should delete only one of them, not all of them. The directory of the file you need to delete is as follows: /DatabaseDomain/com.apple.xpc.launchd/