System starts in emergency mode...how do I recover ?? (as a newbie)

[antonio montagnani]

Suddenly my laptop when rebooted doesn't start in the usual way After 
six months of hard work) but it stops when bootib with this message
drm:cpt-serr_int_handler ERROR PCH transcoder a FIFO underrun
and the appears some lines with request for password for maintenance 
mode or CTRL-D option...

If I open journalctl -xb I see some errors in particular saying that 
fsck failed with error code 4 on dev/mapper/fedora and suggestint to use 
fsck.

How do I revover from this situation?? (I am writing from this machine 
started with CTRL-D option)

Tnx
-- 
Antonio M
Skype: amontag52

Linux Fedora F20 (Heisenbug)
on Fujitsu Lifebook A512

http://lugsaronno.altervista.org
http://www.campingmonterosa.com