I'm running xubuntu, and removed xfce from the software manager (face palm) while trying to clear up space (I believe this is what I did since I cant find any trace of xfce in the terminal). At the time it didn't affect anything. When I restart my computer the ubuntu load screen comes on like normal, then the log-in screen. When I enter my password a text box pops up that says ":unable to launch "startxfce4" x session --- "startxfce3" not found; falling back to default session." Upon pressing okay, another text box pops up that says "failed to load session gnome" with the only option to log out. I'm stuck trying to re-install any gui from the terminal. Also my internet is a wireless network that only works after logging into the internet provider's site, which I'm not sure I can do without a gui. Any ideas or suggestions?
One thing you can do is to (use another computer to) download all the packages for xubuntu that you've uninstalled, from Ubuntu server into a flash drive and boot Ubuntu in the recovery mode (When you see the boot menu, choose the item right below the default item). Then you can install the packages from command line.
If you have a cd drive, you can also try apt-cdrom.
It's a good idea to have a small partition on your hard drive and install (another copy of) ubuntu to it for the rough days, so in a situation like this you can boot from that partition and repair the main installation/partition.