Just now I reset one of my domains and its content. What I did was unassign the domain from my hosting account, backup the database and delete the domain’s directory in my account. I was going to create only a fresh installation of my domain but keep using the same content as before. Everything worked well from the re-assigning to restoring the database.
But when I started to browse each individual posts and category archives, they all returned a 404 error of "Page not found". I checked the permalinks of each posts and found nothing wrong. Permalink structure was also the same as before I reinstall the domain.
Then I googled and found a suggestion to re-save the permalink setting to force WordPress to regenerate the permalink rules. That reset everything back again…
And guess what..? It works!
Credit goes to ozgreg 
Very nice blog
great information…thank you
.-= denbagus´s last blog ..8 Very Useful JQuery forms =-.