My website suddenly dropped ranking in yahoo search engine

I got a website which is ranking pretty Good in Google and was ranking in Yahoo with first page rank. I check it, and I discovered that it has suddenly dropped. It is now in page 10.
I became surprised when I saw this so I just need what really happened and how I can really get that first page again.
Pls, does anybody with an idea of what really happened?

What you need to do is to do your SEO work which are
1. Try to be participating in blog commenting and forum posting because as much as I know, Yahoo do considers do follow links
2. Participate in Yahoo answer community
3. Do a competitor analysis. This will help you know what your competitors are doing
4. Try to do your on page SEO work once more

What must have cause this is low quality content of your website, poor back links, and less traffic

That usually happens when it comes to Yahoo. You must know that Yahoo have done this to many other sites. Don’t be afraid okay. Maybe that’s how Yahoo’s method to rank new websites. But you must know it that your website will have its ranking again in Yahoo

getting rank in yahoo you need to focus on page optimization and Yahoo answer with back links