Robert_Charlton - 6:26 pm on Jan 22, 2013 (gmt 0)
Many sites prefer to have their more precise inner pages rank better than their home pages, because the more precise pages often convert better. So an inner page replacing a homepage wouldn't be a loss.
In your case, it sounds like this isn't what happened... and that instead your homepage may have either dropped or disappeared (perhaps due to over-optimization of inbound links to the page).
Can you describe more clearly what the situation is.