How to restore X11 startup?

Question

X Window System

Ubuntu 15.04. According to the description of one friend, I began to mount a shortcut for launching the program. Created a file touch AndroidStudio.desktop in the /home/username/Desktop directory. After that, I tried to open it with nano, but after changing the contents, I could not write it down: for some reason I did not have enough rights. Decided to reboot.
And now, after rebooting and entering the password, the download stops and the desktop does not load. No launcher, no toolbar. I tried to create another user, but for this new user, after blinking the screen a couple of times, it throws it back to the login page.
How can such a fable be corrected?

Answer 1

Is there free disk space (for users, not for root)?