[Android Central Question]

So I'm recently into photography and the only camera I know I'm allowed to use is my phone cam. Until the camera was gone and of course I got sad and disappointed mainly cuz it's the only camera I can use and it had high resolution. I'm using a Firefly Aurii Secret lite.
My default phone cam disappeared but I found a way to open it again I had a camera shortcut that I can use instead of the app but when I pressed it there was a Chinese thing that appeared by the bottom of my phone screen. I tried to reboot it then it came back but I tried to press it then it said "Please turn off/delete any third-party app" which o can't find where. I tried other cam apps but none of them worked. The phone is almost a year old since 2016-2017 and it's new year right now and I want to take pics of my new year celebration but that happened. I have to be honest the phone fell hard on the ground many times but it had a rubber/jelly case which is why it's still a bit in good condition. Please find a way to get this fixed or at least recommend me things that I should do!😢😭

[Rukbat]

You'll have to back up everything (see Backing up an Android Device), then find a stock ROM and flash it - then restore everything you backed up.