Ubuntu 13 after rebooting I get a black screen with an X cursor without any access to terminals I think. I don't know how to fix or even start fixing this.
From comment: "i tried to do the ctrl alt f2 to access terminal but i just can't log in, i my to enter my user name ang password but it still goes to the black screen with the X cursor. I don't actually manage to input the username and password, it just suddenly goes to the black screen after 1 or 2 seconds."
Looks like lightdm is stuck in an endless loop and keep switching back to VT7. Please press ALT+PrtSc+E which will terminate all running processes. After that switch to a virtual console just like Danilo said and try the commands he wrote.
