There is a big Question what’s the root password , when you install ubuntu , as it never asks you about that.
the ans is that there is none but , without setting it you cannot login as root either. so just a simple command sudo yourself and change the password :
sudo passwd root
I was panicking that i have forgotten the password but it was all upto me ..
i think this is where i struggled for 10 mins to become root ..
thanks to all the forums who help us amatures learn!!