crankin,

When you were once listed and become "unlisted" that's just not a good sign. There is some disagreement whether you are just penalized or banned, when that occurs.

You may "just" be "delisted" which is a fairly strengent penalty. Many believe that you aren't "banned" unless your site expresses a gray bar for PR... I don't know and I don't know if anyone does, for sure.

IMO - Your recovery plan should be: find the offending problem/s, fix it/them and contact GOOGLE for reinclusion.

There may not be that much difficulty involved, especially if your site has been around for a while.

Ken