I didn't check all 1.8 million sites, but the server is sending my Firefox 41.0.2 this response:

HTTP/1.1 503 Service Temporarily Unavailable

Hopefully the webmaster is aware of this and can investigate whether any recent configuration changes on the server are causing this issue. Please submit a support request to the site operator if you can.

is the problem from www.wapka.com or from mozilla firefox pc because all other browser "including mozilla firefox mobile" opens it ....... Mozilla i need your reply now!

I believe this is a problem on the server -- at least, that is what the server is telling me:

HTTP/1.1 503 Service Temporarily Unavailable

I understand the server is not sending that message to other browsers. Which is why I think a recent configuration change on the server might be responsible.

As a follow-up:

The server appears to check your browser identity in order to serve you the correct page. If I set my Firefox 41 to lie and identify itself as Chrome 46, the page loads normally. I used the ua-site-switch extension to conduct this test. Please see the attached screen shots showing the request headers and response (from clicking the first URL in Firefox's Web Console).

Ok thanks! i guess thats coming from www.wapka.mobi server. i will inform my admin of this additional development/information.