Usage scenarios
Without burning CD/DVD or USB stick:
- reinstall Ubuntu (on the same disc)
- install Ubuntu to another disc or partition
Tutorial
source: https://help.ubuntu.com/community/Installation/NetbootInstallFromInternet
Simply:
- download linux and initrd.gz files and save them into the /boot directory
- reboot to Grub and set paths to that files in console mode
- reboot into the installation and follow its steps
Tips
- actual syslog when installing is on tty3 (CTRL+ALT+F3)
- do not forget to select (with space!) Ubuntu desktop option when asking for the desired purpose of computer. This selection is at the end of installation.