Hi @SpoonBearer Glad it is sorted.
Generally you can use the Find My Mobile feature but must have access to another device(can be any Tablet or computer though) https://www.samsung.com/uk/apps/find-my-mobile/
otherwise need to perform a Factory Reset by entering Recovery Mode following these steps:
1. Turn off the device, if unresponsive hold down Power key for several seconds until it switches off.
2.Press and hold the Volume Up key and then press and hold the Power key
3. When the Android logo displays, release all three keys.
4. An 'Installing system update' message will show for 30 - 60 seconds before the Android system recovery menu options appear.
5. Press the Volume down key several times to highlight Factory Reset
6. Press Power key to select.
7. Press the Volume down key to highlight yes, them and press the Power key to select.
8. When the Reset complete Reboot system now is highlighted.
9. Press the Power key to restart the device.
on S devices need to connect to computer or attach USB-C headphones from Android 11 onwards after turning off Device in step 1. Should not be necessary for A Devices though.
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 4.0,Android 12 Official Version.