Wordpress News Site stopped Ranking?

[juliataylor00]

Hi,

We have a very succesful news site that has been running for around 2 years now.
Over a month ago, our articles stopped appearing within in Google search results as they used too.

Would changing a theme make a difference?
RSS feed is working fine. We are using pretty permalinks.

The articles are appearing in Google News fine, but stopped in google organic cearch results - where the articles were hitting number1/2 within half hour every single time.

Please can some one give me some advice on what this could be?

In webmaster tools there are a couple of 404's and a couple of 'unreachable's.
Could this be the cause?
I know Google is changing it's algorithms at the moment (?) but would it affect a big site like this in such a big way?


Thanks