There are at Samsung smartphones the ability the phone in the so-called start "Safe Mode." In secure mode, no apps are loaded that have been retrofitted. So there are only loaded the system data. This should be able to test whether effects on system caused by a third-party app. Secure mode is started by means of special key combination.
Now, however, it may be that you have accidentally this "safe mode" enabled on your Samsung smartphone. If this is the case, then you want to know for sure how to wake it up.
To exit safe mode on a Samsung smartphone, it is sufficient simply to restart the phone. So press once and hold the "Power On / Off" button until a window will appear where you can select "Restart".
After the phone has rebooted, the secure mode is automatically terminated.