“Not found” error on front page after server problem

My database server went down a while ago and is now running again. I can see through the admin panel that all my posts, pages and comments appear to still be there.

But on the front page of my site although the template displays I get the error:

“Not Found

Sorry, but you are looking for something that isn’t here.”

All parts of the front page that use PHP to call up links, text and images don’t appear to work. However if I go into a post or page those same links all seem to work.

Can anyone help me figure out what has gone wrong and how I can fix it?