unknown filesystem

unknown filesystem

I had Mint 15 KDE edition installed on my laptop and I wanted to install
ubuntu on another computer. So using UNetbootin, I made a bootable USB
flash drive from an ubuntu iso file. The next time I power on my laptop it
fails to boot Linux Mint and displays "error: unknown filesystem. grub
rescue>".
My first guess was that Grub boot loader has been damaged so I downloaded
Boot-Repair-Disk to solve the problem but when I managed to boot and
backup I found out that the system cannot mount /dev/sda1. I ran GParted
and saw the following message:



Warning:
Unable to detect file system! Possible reasons are:
-The file system is damaged
-The file system is unknown to GParted
-There is no file system available (unformatted)
-The device entry /dev/sda1 is missing



Here is the address for my boot info created by Boot-Repair-Disk:
http://paste.ubuntu.com/5992203/
I have no idea what has happended and what should I do now. If I'm forced
to, I will uninstall the current OS. But my files contain programming
projects that I have no backup of their latest versions. How can I rescue
my files on /dev/sda1?
Good Luck!