HTTP Error 404.0 - Not Found

Hi,

I just yesterday installed drupal on localserver just to practice using this as its the first time. Every thing was going perfect, I made a few changes (eg. changed theme, created a few pages etc, nothing major) then I start my PC today to find I get this error when trying to access my site. It's an ISS 7.5 error, but I can't see how this has just appeared from nowhere as I have not changed any apart from creating pages etc..

Anyway here is the error (which I get when I type in http://localhost/drupal), if anyone could point me in the right direction I'd really appreciate it.

Error Summary
HTTP Error 404.0 - Not Found
The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.
Detailed Error Information
Module IIS Web Core
Notification MapRequestHandler
Handler StaticFile
Error Code 0x80070002
Requested URL http://localhost:80/drupal/
Physical Path C:\inetpub\wwwroot\drupal\
Logon Method Anonymous
Logon User Anonymous

Most likely causes:
The directory or file specified does not exist on the Web server.
The URL contains a typographical error.
A custom filter or module, such as URLScan, restricts access to the file.
Things you can try:
Create the content on the Web server.
Review the browser URL.
Create a tracing rule to track failed requests for this HTTP status code and see which module is calling SetStatus.

Thanks

giles