I recently downloaded, ubuntu-12.04.3-desktop-amd64. I am trying to install it using software from pendrivelinux.com. However, this version is yet not listed and when I create live usb using any other version, it does not work. Is there any other way to create a live usb?
There's a simple way to get round this.
Rename the file you downloaded to say Ubuntu-12.04 rather than Ubuntu 12.04.3
When your in the installer select "Ubuntu 12.04 64bit" and the iso should be selectable for you.
The reason why you cant select your file is a bad design by the creators of the tool. They use some form of regex to filter out files by name but do not consider the version after 12.04 - which causes they're filter to fail.