My website has been hacked!! My home page was defaced and every php, html, and htm page downloads a JavaScript virus. Plus my hosting company just shut me down because they said I am sending spam, which I'm not!

How can I get my site back up.

Do you know if any other sites on the server you are on got hacked as well?

If so it could mean that hosting company has bad security and the hacker got root access.

If it was just your site then it means you probably have either a vulnerable script or a hacker got your password.

To get rid of the iframe you can do a Unix search and replace, the command will look something like this:
Its also likely the hacker uploaded a php shell backdoor and files that are used to send the spam.

If you are running 3rd party scripts on the site like phpBB or Joomla and are not sure if you have the latest version you can tell you hosting company that believe a 3rd party script you are using has a vulnerability and if they get your site backup you will take care of the issue immediately. If they are hesitant to do that, you might want to ask them to 1. remove your entry form httpd.conf so the site is not accessable on the web, and 2. change you password and possibly your username too so the hacker can't get back in, or access your site via the IP and username. Generally the hosting company will work with you and there may be a nominal fee to get the account back up.