You broke grub

Your system is fucked, that’s what happened.

More specifically, it cannot find the config file (/boot/grub/grub.cfg) it uses to load the menu & stuff to boot.

Usually it means one (or more) of:

• the grub.cfg got moved/deleted
• grub directory got moved/deleted
• /boot directory got moved/deleted
• boot partition failed to load

You’ve got some schmutz on your screen.

Pretty unhelpful responses so far. Enter

exit

to exit the current screen and return to a selection of installed OS/Kernels. You should be able to boot normally from there on. Once logged in, try

update-grub 

which should repair your bootloader config.

I raise you “what happened to my bus ?”