When I activate my vBSEO all the links goes "not found" !!

Two days ago suddenly, all the links went offline in my forum. When you click a link, in forum's homepage, it says "not found" . There was no reason (As far as I know). I changed nothing.. I did nothing.. But when I turn the vBSEO off It wents normal.. But today I noticed that all the pages of my forum, in google's index are GONE !! Not gone actually... When you click any of them It says "not found" too!!! ( Even if the vBSEO is turned on !!! ) Now please help me...

- How can I re-run my vBSEO with no problems?
-How can I make the links work on Google's index?

Please I beg you... It is not just search engine opt. I lost... I lost all my index too!! Please find me a way out... Thank you..


P.S: vBSEO is 3.1.0 ---- forum's adress is " korkma.net "

Hello,

please make sure that your server still supports mod_rewrite module and rewrite rules are allowed in .htaccess.

OK. I solved the problem.. Thank you.. The problem was becouse of .htaccess . Thank you again.

Great!