Please check the following points:
1. Make sure you're logged in when you're checking. Probably the topic is not approved or it's private.
2. Make sure other admin/moderators haven't deleted the topic. In other words, the topic has been deleted by other admin/moderators and when you try to visit by clicking on the link it'll not be found anymore.
I am the only one approving and ofcourse i am logged in,
i get 404 error
i found it from last posts unAPPROVED,
but the link gives me 404 error