torrent downloader not working

Any of the torrent downloader is not downloading any torrent on my computer. They gets stuck to 0% and dont moves forward from 0%. I had already used VUZE, BITTORRENT, UTORRENT, BITSPIRIT, BITCOMET and FIRETORRENT. What is the reason. Is this happening because ihad changed my connection speed in registry (HKEY_CURRENT_USER\Software\DownloadManager/connection speed [/B]to 999999999). Pleas tell me the reason. Also tell me how to find this default speed.

This is my question. Please send me answer to ankumanku.yadav1@gmail.com