I wanted to update my OS to the new 14.04 LTS. I was running 12.04 LTS before and followed the advice that upgrades should be done in steps. I first upgraded to 12.10, which seemed to work fine, and later to 13.10. This was all done through the Software Manager. After the last upgrade, I am no longer able to boot up my computer. The GNU GRUB menu opens up, but after selecting Ubuntu, it just stalls with a blank purple screen. If I select one of the other kernels, it also stalls after "Loading initial ramdisk...". I can't get into the Recovery Menu, either. I'm still rather new to Linux and may have possibly made the situation worse. Unfortunately, nothing has worked yet.

I tried reinstalling from a flash drive and on my first attempt, the wizard recognised a previous installation. Unfortunately, the wizard also didn't like how my partitions were set up (I didn't change anything) and gave an error before closing. Unfortunately, I didn't write the error down, but it was about the boot partition. On the next attempt and ever since, the installation wizard has stated that

"This computer currently has no detected operating systems."

This is strange, because I could see the disk and even access my files when booting up from the USB. At this point, I decided to back up my important files using dropbox. Before losing all my files, I wanted to try the Boot-Repair tool, which also produced no results, and the files are no longer visible when booting from USB. The link to the Boot-Repair log is at http://paste.ubuntu.com/7457249/.

If I then proceed through to the "Something else" installation option, I can see that the partitions still exist. This is what they look like:

/dev/sda
free space (size indicated 1MB)
/dev/sda1 efi (33MB of 98 MB used)
/dev/sda2 efi (352634MB of 746330MB used)
/dev/sda3 swap (3725MB, none used)
free space (0MB)

Is there any way I might be able to get my computer to work and preserve my files as well?