its very strange get back links from relevant website and send me URL i will add you link in my website free of cost just because you have expended 6 months.
Whel i have never encountered this problem but the easyes way i think is to seend google an email stating that the owner of the site has changed and you would wish to get it unbanned ... and you can also tell them that it is a school forum.
Recently one of my site got indexed in 2 days, and is still there so your problem is really strange. Try submitting sitemaps + build lots of high quality and relevant back links
Try to comment on other sites with PR. You can have more chances that way that google crawl your site