A factory data reset may help with a blank or frozen screen, apps crashing or freezing, keypad/touchscreen problems, can't hear, device making noises, can't make or receive calls, and device won't sync.
Perform a factory data reset only if absolutely necessary as it removes all data including:
System and app data
Media (Music, pictures and videos, etc.)
If a pattern, PIN, etc. is or has ever been set up on the device, Google account sign in is required during initial setup.
Wi-Fi Calling settings don't transfer after switching devices and/or performing a factory data reset. You need to enable W-Fi Calling manually if you want to use it.
Ensure the device is powered off.
Press and hold the Volume up+Bixby buttons.
While continuing to hold volume up and bixby, press and hold the Power button until the device vibrates and the Samsung Galaxy S9 logo appears then release all buttons.
This action boots the device to the Android Recovery screen.
Allow up to 15 seconds for the recovery screen to appear.
From the Android Recovery screen, select Wipe data/factory reset.
Utilize the volume buttons to cycle through the available options and the power button to select.
Allow several seconds for the factory data reset to complete.
Select Reboot system now.
Allow several minutes for the reboot process to complete.
If applicable, set up your device.