Device rooting fails, but doesn't brick? I've was trying to root my Vodafone 858 Smart (Froyo) using super one click but it stopped in the middle of the operation and the program was non-responsive so I closed and it was closed while installing super user and it couldn't install it due to low phone memory.

So I tried rooting it again after clearing some phone memory it roots but I don't have super user or busy box but I can access super user capabilities from adb so how can I root my phone properly?
You can install Busybox from the market too: https://play.google.com/store/apps/details?id=stericson.busybox&amp;hl=en

And to your other question 


  i just wanna know what does busy box do? 


taken from market description: 

BusyBox is a software application that provides many standard Unix tools, much like the larger (but more capable) GNU Core Utilities. BusyBox is designed to be a small executable for use with the Linux kernel, which makes it ideal for use with embedded devices. It has been self-dubbed "The Swiss Army Knife of Embedded Linux".

The official BusyBox website about page has some more info about what it is too.