[Assist] pam login big problem!

[aha]

Hi all!
I'm sorry for this question, perhaps newbie question, but I don't find 
explanation on the net! :-(
Yesterday I halt my machine and today I can't login: boot but when
login: display I enter a login user or root and don't ask me password
but directly login incorrect!
I suspect a pam problem but I've don't modified anything yesterday!
I can reboot on a separate-rescue partition (hopefully I do that!)
The lines in red I can see with journalctl are:
PAM unable to dlopen(/usr/lib/security/pam_unix.so):
/usr/lib/security/pam_unix.so: undefined symbol: log_debug
I can login on my rescue partition but don't networking.
I write from a second machine.
Could someone help me please?
Thanks in advance!

-- 
anHArCKhist666