If, suddenly, you receive a Page Not Found error when trying to go to your site's front page, and the address you entered is correct, chances are there has been a change to the URL Alias of the node that is used for the front page.
This can be startling when it happens as it suddenly appears as if you do not have access to the site, but in fact you still do. First, though, let's understand why this is happening.
The OSU Drupal installation is set up, by default, to recognize the word "home" in the URL path as the front page. So, for example, a node with the address "http://oregonstate.edu/dept/collegename/home", would automatically be recognized as the front page and would display as "http://oregonstate.edu/dept/collegename".
When CWS intially installs an OSU Drupal site, the "home" page is automatically set up. All you have to do is replace the filler content on that home page with your own. If, though, the page is deleted or the URL Path Settings on that node are changed to something other than "home", the front page will disappear.
Any role in an OSU Drupal site has the ability to change the URL Path Setting right from the content submission form, so it's important that awareness is raised about this potential issue.
So now that some light is shed on the cause of this issue, the solution is actually easy to figure out: just change the URL Path Setting back to "home".
If you were not logged into your OSU Drupal site before losing your front page, you can still log in using the original login process. If you are not sure about this, please read the How do I log in to my OSU Drupal site FAQ. If you were already logged in when the front page was lost, you will actually still be logged into the site.
Your front page should now be returned back to its normal state.
If, for some reason, the URL of the front page needs to be changed from "home" to something else, the administrator of a site can do this - though it's really not necessary as the front page will not contain the word "home" in the URL. For instruction on how to change the Default Front Page settings, please read the How do I change the Default Front Page Settings FAQ.