Both pacman and powerpill don't seem to be working on my Arch installation. I'm sure my Internet connection is working. The download just starts in powerpill but speed remains zero. In pacman, there's an error saying 'No file address found'.
It's difficult to give a specific answer without a more detailed error description, however, it does sound like your mirrorlist file is out of date or misconfigured in some way.
I wrote a quick script to update the file without the use of pacman:
In a nutshell, that script will pull an updated list of mirrors, rank them in order of speed and save the list in your mirrorlist file.
The given url assumes you want mirrors in the United States, using ftp or http, and only IPv4. You can modify that by going to http://www.archlinux.org/mirrorlist and customizing it as you see fit.
Once the script completes, then run
and hopefully it works!
By the way, I forgot to mention that powerpill has been deprecated.
Update your mirrorlist file