Booting to no display
Without knowing what the exact error message was it will be difficult to diagnose. The basic sequence of events is :
- You failed to boot into ubuntu
- You tried recovery mode
- Recovery mode runs some extra checks on the system and repairs stuff when it can
- Whatver problem was fixed by the recovery mode basic tools
- You rebooted and it started normally
This could have been caused by anything from a bad shutdown to some intermittent hardware fault, so its hard to tell exactly what caused it to begin with.
Recovery mode does not automatically start X (the graphic display system) which is why you were dropped into a shell (This is done so you can repair a broken Xconfig from recovery mode). You can start X manually by typing startx as a command next time if you don't want to reboot. If you are running vanilla ubuntu that should start X and run your default display manager (Unity or Gnome).
The Ubuntu Wiki related to Troubleshooting BlankScreen provides useful information about why this problem occurs and how to fix it, which in my case solved my problem that was giving blank screen at the boot and I couldn't even see the Login Screen.
Related to what you refer about your issue, there is a part that reads just under "Non Symptoms":
If it occurs after entering your password on the login page, you have some different class of issue, such as an issue with 3D / DRM. Try disabling compiz (sudo chmod a-x /usr/bin/compiz), logging in as a different user, or turning off DRI.
However, I suggest you take a look at that document and check what of these can give you a clue on where to start for you to fix it.
Good luck!