What to do when nothing seems to fix Ubuntu 14.10 stuck after log in?

Question

So I run Ubuntu 14.10 on HP Pavilion g6, i5 and with Radeon HD6500. Yesterday Ubuntu crashed and since then I can't get anyfurther than the log in screen. Ubuntu simply stucks with only the background and cursor visible. It seems to be stuck in log in and there are a lot of fixes all over the internet for this. Non of them seems to help. I will explain step by step what I done so far.

Update 1 dec 2014: Followed recommendation from @ash and didn't fix the problem. Still think @ash fix will solve similar problems, but not for me. I reinstalled Ubuntu and that fixed the problem, so the problem was probably graphically. If anyone have any idea what may have happend, please answer.

1. Changing dm

First I tried changing dm to gdm (also suggested in a comment here).

sudo dpkg-reconfigure gdm

That didn't work. I even tried lxdm, but no result there either. After I tried that I read that I might check 50-ubuntu.conf and did so. Nothing strange over there. Also tried stop and start for lightdm, no result. Then I found this and tried

sudo dpkg-reconfigure gdm
sudo apt-get remove lightdm* --purge
sudo reboot
sudo apt-get install lightdm*
sudo dpkg-reconfigure lightdm

I'm was not a fan of the hole lightdm* --purge but tried it anyway. It didn't fix my problem, but I guessed it would remove a lot of packages that wasn't really related to the problem. What I didn't guess was that it would change the graphics this much. I could of course realized that install lightdm* would install a lot of unnecessary packages. When I rebooted the computer it said Ubuntu Studios instead of 14.10 and the log in screen looks messy. Also, the computer gets stuck in a black screen with only the cursor visible instead of as earlier. Well, stupid of me to take a bad advice (if anyone have any quick fix for this I would really appreciate it).

Anyway, nothing of this fixed my problem.

2. Reinstalling Unity and ubuntu-dekstop

After reconfiguring lightdm I tried to remove and install Unity and the same with ubuntu-desktop, but no change. This is also a pretty common recommendation all over internet.

3. .Xauthority related solusions

Next step was to follow this advice entirely, but the output of both ls -lah and ls -ld /tmp checks out.

Next step was this advice and it didn't do anything either.

I don't really understand what both this commands are trying to fix, but would be nice to understand that. Does someone have any further suggestions related to this? And does anyone have any explanation what they are supposed to fix?

4. Installing fglrx

Next step was to keep on guessing and this point I thought that the problem was graphic card related. I tried to Google around as much as I could about Radeon graphic cards and similar problems and found a solution that suggested:

sudo apt-get update
sudo apt-get upgrade   
sudo apt-get install fglrx    
sudo aticonfig --initial
sudo reboot

Well didn't do anything other than installing fglrx.

5. So I'm looking for other solutions

This seems to be the four most common solutions to problems like this. I think it's time to at least stop suggesting anything related to lightdm because that doesn't seems to do the trick.

As stated in comments this problem can be almost anything, but at least I tried to explain what I done so far. Have I done anything wrong? Are there anything more to know about these four?

Answer 1

I am facing the same situation, frankly I don't have the time to go through the logs and fix it plus I am afraid I will ruin something again and I can't spare any time right now to reinstall Ubuntu and/or try any fix so I am dealing with it the following way.

What I am doing to get access to my machine after getting stuck on login page is the following:

1- After rebooting and landing on login page I go to a TTY (ctrl+alt+F1).

2- Login as my normal user.

3- kill lightdm running processes sudo killall -u lightdm

4- remove Xauthority file rm .Xauthority, the one under my normal user account i.e: ~myUsernameAccount/.Xauthority.

5- make sure no lightdm instance is still running with ps aux | grep lightdm

root      2412  0.0  0.0  89496  2600 tty1     S    16:59   0:00 sudo lightdm
root      2413  0.0  0.1 351608  4100 tty1     SLl  16:59   0:00 lightdm
root      2418  0.5  1.0 312932 39132 tty7     Ssl+ 16:59   1:57 /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
root      2491  0.0  0.1 188932  4700 tty1     Sl   16:59   0:00 lightdm --session-child 12 19
ash    8723  0.0  0.0  15944   916 tty1     S+   23:15   0:00 grep --color=auto lightdm

See in the previous output, lightdm is lunched as root so killall -u lightdm won't work, so I do the following: sudo kill 2412 2413 2418 2491, but if the system is just booted up then you will see lightdm instead of root and that command will work fine, (also notice that the last line is grep output command and is always shown so ignore it)

Now if you check ps aux | grep lightdm again the output should be something similar to this only:

ash 8759 0.0 0.0 15940 912 tty1 S+ 23:17 0:00 grep --color=auto lightdm

6- lunch lightdm again sudo lightdm&.

7- Switch to GUI (ctrl+alt+F7) again.

8- Login normally, it mat get you back to F1 TTY so again go to GUI using ctrl+alt+F7, wait for few seconds till the crash report is completed and I will be on my desktop.

P.s: using this method, you have to enter the system key everytime you do something that requires root privileges, for example: I can't edit network connections from the top panel directly, I have to call the networking from terminal using sudo, ...etc.

Ofcourse this is not a good practice at all, but I hope it will help someone to get around the problem for a little amount of time.