Upgraded 12.04 > 14.04, GUI only works as guest user

[Fissurecat]

Hi.

I upgraded from 12.04 to 14.04 last night. When I log in to my home directory, the GUI sticks at a blank splash screen. The only way I can use the GUI is as a guest user. I'm a GUI user and am familiar, but not comfortable, with terminal use.

Resources I've checked so far:
1) Release notes; I found no description of my problem. Bug 1308530 is the only issue that comes close, but too many details are different.
2) https://help.ubuntu.com/community/LostPassword (Per IRC #lubuntu suggestion.) Grub doesn't recognize "mount" as a command. The other two variants didn't work, either.
3) http://ubuntuforums.org/showthread.php?t=1946145 Might be relevant, but is a radical enough solution to seem further down the "try it" queue.
4) http://ubuntuforums.org/showthread.php?t=1743535 Baffles me. It may very well cover my issue, but I'm lost before getting halfway through.

Can anyone help? If my problem is covered in 4) "Graphics Resolution-Upgrade/Blank Screen after reboot," I'd really appreciate a text string to search for. Strike that.. I'd very much appreciate any help at all.

Thanks.

OS Details:
Kernel: Linux 3.13.0-39-generic (i686)
Distro: Ubuntu 14.04 LTS
Desktop Environment: LXDE (Lubuntu)

[Enigma12]

I only have more "beans" than you because I've been somewhat active here, but A) I am still a newbie to Linux and B) have read enough posts about problems that others have had with upgrading that I would not make that big a jump in versions. Instead, I would back up all needed data and erase the old and install the new version. My little jump from 13.10 to 14.04.1 has gone smoothly, but I may just be lucky in that small upgrade.

If someone who knows more than I do offers a simpler effective solution, go with it.