Virtualbox Installation

sudo apt-get install virtualbox

Steps for installation of ubuntu-server on virtualbox

Ref Link

Creating a snapshot

Assuming in virtualbox there is fresh installation copy of ubuntu-server

cp -r '/home/user/VirtualBox VMs/ubuntu-server' '/home/user/VirtualBox VMs/ubuntu-server-snapshot'

/home/user/VirtualBox VMs/ is the default location for storing virtualbox images.

Restore from snapshot

First remove old copy of virtualbox image

rm -r '/home/user/VirtualBox VMs/ubuntu-server'

Restore snapshot

cp -r '/home/user/VirtualBox VMs/ubuntu-server-snapshot' '/home/user/VirtualBox VMs/ubuntu-server'