Hum, your problem description is somewhat confusing.
If I've correctly understood your post you're saying that, when you boot, you're presented with a "Login" prompt instead of the "usual" boot options, even when you boot using the "Recovery" option from the GRUB boot menu.
If so, you want to know how to proceed from the command line. So, here's a few "command line" suggestions for you:
First, log in by entering your user name (usually your first name in lower case) at the "Login" prompt and, after you press "Enter," entering your password after the next prompt.
Next you need to connect you computer to the Internet. Do this by entering the command sudo dhclient
Now you can try to fix your system using the aptitude
commands. I'd try the apt-get
first, like this:
$ sudo apt-get check
$ sudo apt-get -f update
$ sudo apt-get upgrade
If you choose to use aptitude
instead, you access the menu by typing a <ctrl>-t, and there is a built-in "help" function.
After you get things cleaned up, use the command startx
to start a GUI session.
Oh, re your nVidia problem: Did you enable the restricted repositories and install the nvidia dkpg? The one I'm using (180.44) works quite well on this laptop with an embeded nVidia GPU.