I had 0 bytes free and even when I deleted something the number of free bytes stayed still zero. So I tried to restart it and I can't login now. I tried console Ctrl+Alt+F1, but I don't know login. I wrote the name that is normally displayed above the password, but it is wrong. What should I do?
Make a LiveUSB on another machine
Boot from that LiveUSB on your PC.
Access your boot drive, whether SSD or HDD (makes no difference).
Either delete files you don't need, or move them to another drive (such as a USB or external SSD or HDD).
After this problem is resolved, you may wish to consider the use of tmpreaper or equivalent to delete temp files between reboots, and also a method to monitor file space available (I use conky on my desktop for this).