check if any setting is changed. go to setting_display you can try turning off Blue light filter or changing screen mode

You can do it1) just download it from any source save it to ur phone, open it and then from options you can set it as a ringtone.2) If u want to add it from computer then just download any software, syncios recommanded which also has android support ...

Delete earlier data of fingerpring scanner, then restart ur device then again register ur fingerprintshould work.