I would like to throw some light on submitting a reconsideration/recinclusion request to Google. Below are the ways to follow.
1) Do a thorough check on crawl errors by logging into Google webmaster tools. Fixing all those errors should be your immediate work.
2) Check for any site issues in your webmaster tools "message center." Follow the suggestions for fixing the site issues if you have any.
3) Scan the webmaster guidelines to see if you have done anything that do not comply with Goolge guidelines.
4) Now if you feel that everything is perfect on your website and it is 100% Google webmaster compliant, submit a reconsideration request via Google webmaster tools.
Site back and relax...........Google would be taking you website into its database once again.