Can you urge me please help what could be the cause.
Does a Y also include a Z, or vice versa?
You must have accidentally switched to an English keyboard. Hit Alt and Shift.
America keyboard layout? So it looks for me accordingly
Yes
You probably accidentally switched to the English keyboard layout. Use the symbol next to the clock (blue box where EN is now in it) or the key combination SHIFT + ALT to switch.
What comes out when you try to enter the bracket. So the raised 8 or 9?
If there's no bracket, the wrong keyboard is set.
https://www.ionos.de/digitalguide/server/konfiguration/windows-10-tastatur-sprache-umstellen/