I don't have enough reputation to comment (my previous answer has been converted to a comment for some reason), but want to help, so I'm writing another answer.
If you can boot to command line, try opening the /var/log/syslog and see if there are any suspicious errors listed at the time of your last unsuccessful boot.
You could also try to disable the automatic boot to desktop manager by editing your GRUB file
sudo nano /etc/default/grub
change the "quiet splash" to "" and then run
If you have lightdm installed, you may have to also do
sudo touch /etc/init/lightdm.override
to disable the LightDM autostart.
If you manage to boot to CLI without the recovery mode with these settings, run
or (if you have gdm installed)
sudo service gdm start
or (if you have lightdm installed)
sudo service lightdm start
from your home folder and see if you can enter the X window system that way.