My html pages stoped working seo on and off

Hi ITS 1.3.5

i have page in my shop that was working fine but no after few days im looking and all the pages that have like:

.HTML in the end dont work anymore and i have lots of them.

I tried turning the seo add on and off but still the same no working.

Lets say im going to [url][/url] DONT WORK.

But if im going to this: (which is the same page but the link is different:

[url][/url] ITS WORKING.

I cant change all the links i have a lot.

Any ideas whats wrong

Any ideas why?

Any one have answer

It seems that your mod_rewrite module has problem. Have you enabled SEO addon?

yes i did. and the disabled but nothing