Before closing/marking this as duplicate read below first.
Using a live ubuntu 14.04 LTS pen drive and various troubleshooting on similar posts I was able to successfully boot once but the mouse and keyboard were not working so I went for a reboot and after reboot again I got the unable to find live file system error message every time over and over again even after I created the bootable pen drive using the same steps.
MD5 hash is also correct.
I am using a Gigabyte ga-990fxa-ud3 rev 5 motherboard so I partitioned my 8GB pendrive into 2 parts each less than 4GB and created a bootable pen drive.I also disabled the USB 3.0, Because when I tried with only partitioned pen drive or disabling the USB 3.0 it did not work.
NOTE:- I tried using the same pen drive with a laptop(hp pavilion p-077tx) of a friend and the pen drive works just fine.