Vroot root/unrooting tool : can root almost all android devices running android 2.2 (Froyo), 2.3 (Gingerbread), 4.0 (Ice Cream Sandwich), 4.2 (Jelly Bean) >> it is also compatible with some newer android builds.
Prepare your android device for rooting :
Device must be charged 50% at least.
Download & Install ADB (Android Debug Bridge) drivers [Link] For your device.
Enable USB Debugging Mode on your device
(For Earlier Android OS) Go To >> Settings >> Applications >> Development >> USB debugging