Like two or three months ago, i opened up the developer settings with the "tap 7 times on the build number" method. And i used it, then i wanted to turn it off. To do this: i went to my application settings, found the "settings" app and cleared data and the cache. With this method, my developer settings gone.
So, i wanted to turn it on again couple of days ago, tapped on the build number and a pop-up showed up like this:
"No need, developer mode has already been enabled"
Then when i go to the main settings page, where the developer settings were in, there was no developer settings.
And yes, i know where the developer settings exactly is. So please don' t answer me like "check again", "tap on the build number for seven times", "restart your phone" or something like these.
And no, since i cant reach to the developer settings, i can't open the "OEM unlock" and "USB debugging" settings.
And i also tried the "Activity launcher" app but it didn't work too.
Please help...

 

Thanks for the reply first.
Yes, i tried to reset the settings app for at least 5 times. Nothing changed. I started to think like "is the knox causing this problem maybe?".
And yes, the best solution could be factory reset but no. I have a lot of data on this device.

 

No one knows?