I've upgraded from Ubuntu 14.04 to 18.10 from Linux CD.
After booting it asks for live user password. So I tried using my usual username and password, but it is not recognised.
There's no option to request to change or update password.
How do I get into my desktop?
Ubuntu asks for live user password when the computer is booting because the Ubuntu live DVD that you used to install Ubuntu is still in the DVD tray, and the computer is booting to an Ubuntu live session instead of to the Ubuntu OS which you installed on the hard disk. It's not necessary to reset the administrative password if the computer is booting to a live session, just prevent the computer from booting to that live session anymore (without changing the password of the Ubuntu OS which is installed on the hard disk) and after that Ubuntu will boot normally.
Open the CD/DVD tray manually by pressing its open button when the computer is booting. You can do this at any time or by entering the BIOS utility, ejecting the optical drive tray, removing the Ubuntu live DVD, closing the optical drive tray and then exiting from the BIOS without saving any changes. After the live DVD is removed, Ubuntu will be able to boot and login normally.
