I have a domain that was performing well in SERPS and had > 100k googlebot visits per month.

In the last 7 days gbot has only visited 17 times and over the past month it has gradually dropped all my pages.

Obviously I have done something g doesn't like.

I am not inclined to give up on the domain partly because I like the domain name and partly because it has 1000's of links.

Have you seen websites treated like this and recover? How long would you give it before giving up on it?