If anyone faces the problem of the forum page missing CSS Styles then they can use this to solve their problem:
1.Get to the UCP(ucp.php?i=174)
2.Set style back to "subsilver2" from a drop down list.
3. Save and do a full cache refresh!!
The cause of this bug is... the style "prosilver" being removed (but for some strange reason, it shows in the UCP). I definitely liked that style.
Since, the style wasn't so wide spread, very few people have experienced it.