Problem with Category's Links

PLease help..

I don’t know why, my every category’s links on one wordpress installed website have failed to linked correctly. The link redirect to 404 page not found. Exactly, I don’t know what I’ve doing on the recent which cause this problem. When I am using admin panel, then go to Posts -> Categories, all things goes fine, each posts on their category. But when I try to visit my site, then click the link on the category widget or any place (below the post’s link), they always redirect me to 404 not found.

I have disabled some plugin, but nothing good happen.
I have change the theme, but nothing good happen.
I have reinstall from updates menu, but nothing good happen.
I have backup then upload manual the wordpress (without deleting any files on the hosting–just overwrite), but nothing good happen.

What should I do next?
Please don’t say that I should have a new installation of wordpress, because that’s complicated for me, at least on this time. My hosting is not embedded with fantastico, only CPanel. Then the content on the site is complicated too, such as some audio which attached for my podpress. If I do fresh installation, then import the last database, then actually my podpress setting (and the playable files inside it) is alright?

Please note, that all links are fine, except the category links.

Thank you.