I recently built a pc with a blank hard drive. I decided to install ubuntu onto this new system with a disk i had burnt. The installation had been fine up until the point where i had to restart/reboot the computer. It came up with a message 'Unlocking the disk /dev/disk/by-uuid/db655a25-cdcd-4277-b3eb-9610175dd93b (sda5_crypt) Enter passphrase:' I have tried the two passwords i enter during installation and both of them didn't work (i didn't think they would but i had no other ideas.) Could anyone please suggest what i do now. I would like to delete the operating system/ re-install it, how would i go about doing this? Any help would be very appreciated.