I know that getting your adsense account banned is the worst nightmare of any internet marketer . Getting an adsense account banned means living behind quite a bulk of money and online oppurtunities. Google bans its adsense publishers only if they broke their ToS or were related to click fraud. Google is quite serious about click fraud or invalid click activity and it is the reason why most people get their adsense account banned. But many time innocent publishers get their account banned without any reason or doing anything wrong , if that is the case with you then you can appeal to google for changing their decision of banning you. But if you were really into click rings or click fraud then there are absolutely no chance of getting your account back. But if you are innocent then getting your account back is quite a possibility and many have actually got their account reinstated.
To appeal you need to fill up a form at google.com/support/adsense/bin/request.py?contact=appeal_form. In this form google will ask simple information from you like your adsense id , your login email etc. First , before filling up anything you need to gather concrete information of what led to your ban if you detected something suspicious then you must inform google in the appeal form. Be polite yet professional when filling up the form , tell google all you know and submit it . Then go to your gmail inbox and you will receive the conformation of the appeal, this means that your appeal has been submitted to google . Now you have nothing to do but to wait for google to answer your email it may take quite some time to get the email from google as they recieve thousands of appeal every single day so it may take a whole month before you could hear anything from google.
If google reinstates your account then you can rejoice but if it doesn’t reinstates your account don’t feel sad or dejected as new roads will open up for you. If you had a blog then you can still earn money from it using services like adbrite , chikita and yahoo publishers network.