boot – Ubuntu not showing the recovery menu

I am new to Linux (Ubuntu) and have forgotten my administrator password (main login).
And now, my computer does not even connect to the usual user anymore …
The hard drive light is not flashing, it is dark.
The screen only displays the purple color, nothing else, no mouse pointer, nothing …
Can only restart with the main power button, holding it down to turn it off, and then turn it back on.
If then select "reboot" (before logging in), hold down the SEC key to access the advanced options menu.
When you select "Ubuntu with Linux 4.15.0-45-generic (recovery mode)", a ton of text scrolls on the screen, but does not show, as I imagined, the "menu of recovery ", but displays the user menu instead …
I've read many articles online, but none seem to describe the problem where the recovery menu would not show up, but still displays a normal Ubuntu screen with the users that are configured there.
Please help me because I have to reset my administrator password in order to be able to access my account again. Thank you