I want to reset Ubuntu. I have searched it on Google many times and I am new to Ubuntu so I am wondering how to reset it without too much complication. I have already tried re-installing it but my computer will not boot from the DVD. I am using Ubuntu 14.04.2 LTS.
I want to completely delete everything and have it start like it did when it was originally installed. Completely erase everything and restart, reinstall, and reconfigure Ubuntu.
Your computer will not boot from DVD then you have one other option. Booting your computer from USB memory stick. You can use many softwares to achieve this, but I personally like UNetBootin which supports windows, mac and linux. You will need to have a ubuntu ISO file that you want to install, and a suitable usb memory stick (above 4GB storage is fine). Create a bootable USB stick. Configure your BIOS to boot from USB and reinstall.
1) Reinstall ubuntu desktop
Execute in terminal or tty:
sudo apt-get install --reinstall ubuntu-desktop
**2) Reset compiz **
dconf reset -f /org/compiz/
(Source: ubuntu handbook)**3) Reset Unity **
Refer here
If you can login Try creating a new user first and see if that is working OK. It one of the easiest ways to experience Ubuntu like it was when you installed it.