Hello
I’ve received an update 2-3 weeks ago and I’ve updated my computer, then I restarted it and I can’t logged in to my user account i was writing the password and pressing enter the screen becomes black and it return to lightdm again
I can log in to root account and I’ve restored the backup from root account
Also I can log in with tty
what could be the problem
I have read quite a lot of similar stories here - so:
this has been discussed a hundred times already and all you need to do is invest some time and find those posts and read them - then, if you still need help, come back with questions and system information.
Welcome to the forum! 
Did you by any chance overwrite /etc/passwd and/or /etc/shells with their respective .pacnew file?