IP bans will be reconsidered on a case-by-case basis if you were running a bot and did not understand the consequences, but typically not for spamming, hacking, or other abuse. If you are responsible for one of the above issues.
Running a web bot/spider that downloaded a very large number of pages - more than could possibly justified as 'personal use'.Automated spam (advertising) or intrustion attempts (hacking).
Your current IP address has been blocked due to bad behavior, which generally means one of the following: