I have a new Dell Inspiron 3542 laptop with pre-installed Ubuntu 12.04. Recently I tried to upgrade to ubuntu 14.04 LTS. After all the download was done online, Update Manager was Installing and upgrading. But in between the upgrade, I switched off and went to sleep. Now my Ubuntu is not booting. I tried running in recovery mode, but it fails to boot.
The 2 options I'd recommend for you are:
- Try LiveCD and reinstall the GRUB
- Try Memtest86+ to check for fails in your HardDisk/RAM
If you insert your CD/USB with Ubuntu on it, and try ubuntu instead of installation, you'll be able to navigate and check the issues of the HardDisk, the most common issue on booting usually is because of the GRUB.
So I recommend you to try with a Live CD/USB and reinstall/update the grub, you can find some guide/examples:
- How do I run update grub from live CD
If you cannot fix your grub/boot I recommend you to store your data in an external drive, format your HardDisk and make a clean installation again.
From what I can tell is that you turned off your system, while it was upgrading from 12.04 to 14.04, that is never recommended!
Even if you get Ubuntu to boot again, the rest of the system might still be broken due to an unfinished upgrade.
My advice is, do a clean install. You don't know what exactly is broken. Start from a LiveCD, save all of your data you want to save to an external HDD, and when that is done, format your Ubuntu partition, reinstall it on that partition, and afterwards, copy back the data from the external HDD.