I installed the newest kernel yesterday, and it was booting up fine until this morning, when I get a black screen with a blinking cursor. I can enter the grub menu, but can’t use tty3, 4 etc. My keyboard won’t do anything with the cursor and ctrl+alt+backspace/delete won’t work. I don’t know what to do.
Hi and welcome to the Forum 
Try to boot using an older kernel, which most likely is still listed in your boot menu…
After that you could check your log’s to see what went wrong in the previous boot by using for example journalctl -b -1