I'm using Ubuntu 14.04 on a Toshiba S55-B5289 laptop. I've been using a second monitor with the laptop since I got it, and it's basically been plug-and-play. I connect the monitor via HDMI, and usually it just fires right up. Last night, I unplugged the monitor to take the computer upstairs. I noticed it was still behaving as if the second monitor was there. So I logged out and logged back in--problem solved. Today, I plug the monitor back in, and Ubuntu doesn't detect it. I've spent the last half hour unplugging, plugging back in, restarting, tweaking settings, and browsing forums without much luck. Most of the tips seem to have to do with getting a second monitor working in the first place. It was working yesterday. But now the laptop just doesn't seem to notice it's there.
Some system updates came out today, and I applied those using Synaptic Package Manager. After the update and another reboot, the dual-monitor system is working again. I don't see anything in the updates that appear to have anything to do with display, but my guess is that maybe running the updates flushed out whatever the disconnect was that was keeping the second monitor from being picked up.
As I suspected, this was no fluke: Your
monitors.xml contained an erroneous configuration without HDMI.
Here is the corrected version that only contains one single configuration (the original that worked without any problems)
- Replace your existing version with my corrected one
- Keep a back-up of the corrected just in case this ever happens again…
By sheer coincidence I had a similar problem right here with this computer only yesterday. Believing in trying the simplest solution first I applied a thin layer of CAIG DeOxit D100L to both ends and that fixed it. I recommend it to all my friends.
I gave a vial of this to my girlfriend two years ago, and of all the gifts I've given her for birthdays, holidays, and anniversaries, I'm sorry to say this is what she uses the most. A few months ago she "fixed" her daughter's iphone when it refused to charge merely dabbing this on the charger plug. When her 14 year old daughter asked how that fixed it, my girlfriend's response was "It's Magic".
So you see, while this is not the same magic recommended by another, it is a useful tool necessary in any geek's arsenal, and it is available online.