My website had very high search engine results, especially in Google. But I left the website for a couple of months and didn't notice the comments were full of SPAM, about 20k comments of SPAM. Then i checked my google results and I'm out of google ! After years of having good results, no spam, how can I now recover from that? The spam problem has been solved completely. No more spam, and the website is very legit and very nice.
Well, at least I think I was penalized, I don't see any other reason.