Back up your saved data to USB or PlayStation Plus Cloud Storage (optional)
Sign in to PlayStation Network
Turn off the PS4 completely
Press and hold the power button until you hear two beeps (second beep after about 7 seconds)
Connect a DualShock 4 controller using a USB cable
Press the PS button on the controller
Select “Initialize PS4 (Reinstall System Software)” from the Safe Mode menu
Select “Yes” to confirm
Wait for the initialization to complete
Follow the on-screen setup steps to reinstall system software and set up the PS4
If prompted, restore from your backup (optional)