If you're using GoDaddy for your web hosting and you've installed Drupal on your shared hosting (Economy, Deluxe, or Unlimited hosting plans), then you may have run into the issue where you can't enable Clean URLs for Drupal. Fortunately, there's an easy fix. Unfortunately, the fix is so easy, I'm not sure why GoDaddy hasn't fixed this.
In your FTP client or the file browser in GoDaddy's tools, navigate to the root where your Drupal instance has been installed and look for your .htaccess file. Look for this important line, noted in red: