Hi,
It may be that the brush roll drive belt is broken.
Here is a link to the ifixit guide [guide|72417|to repair / replace the brush roll]. The belt is shown clearly in Step 8 of the guide.
If it is broken then here is a link to [http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2374313.m570.l1313.TR0.TRC0.H0.XShark+Rocket+HV301+belt.TRS0&_nkw=Shark+Rocket+HV301+belt&_sacat=42146|suppliers] of the part.
Hopefully this is of some help.