Do you know what the boot menu is?
When the system starts, before you see the openSUSE logo, there is a black screen with a few (likely: four) lines of white text. It is shown for a few seconds.
With the down-arrow key, select the advanced options. It’s likely the second line. Press Enter.
Then go to the first line which contains “(Recovery mode)”. It’s also likely the second line. Press Enter.
The system will boot and then ask you for the Root password. Enter it.
Then enter:
rm /etc/nsswitch.conf
poweroff
(I’m assuming that you have no special configuration in that file, given that you are “not a tech guy” ;))
Then switch the system on and it should work.