i went to upgrade my plugins and it never came back .. now when i go to my blog i get an error stating:
The service is unavailable.
i tried renaming the "upgrade" folder under wp-content but that didn't seem to do anything.
This is definitely not error message produced by WordPress, so it comes from server software. Please check server logs (if you have access and skills) and ask your hosting support to look into it.
It is hard to make a good guess from this little information.