300 Multiple Choices

I’m getting the following error message when I click on a post on my blog:

Multiple Choices

The document name you requested (/index.php) could not be found on this server. However, we found documents with names similar to the one you requested.
Available documents:

/index.html (common basename)
Please consider informing the owner of the referring page about the broken link.

here is a link

I think the “index.php” is missing or moved, but not sure where to fix it, thanks!