If your Samsung Smart TV is behaving out of the place, its a good idea to reset Samsung TV back to original factory setting to resovle the issue. for most of the Samsung tv's manufactured between 2012 to 2018 steps are same.

Steps to reset Samsung Smart TV to factory settings.

1. On your samsung smart remote, press the "MENU" button.

2. Select "Support" section displayed on the screen, click enter button in the middle of the remote's arrow buttons.

3. Select "Self Diagnosis" link option.

4. Select "Rest" at the end of the list, then press "enter"

5. enter the PIN, default pin is "0000". if you have changed the PIN enter your pin. 

Note: if you have forgot the pin, resetting it is bit tricky, contact samsung customer care.

6. Select "Yes" to confirm to reset Samsung TV settings to factory settings.

Resetting the Samsung Smart TV with out remote.

To bring the menu, hold the start button at the back of the TV, Menu option will popup , then follow the steps above using the tv buton at the back of TV.