Originally Posted by bakuryu

contact gmail support and they may provide you the ip log.

However one can easily use a proxy network and hence knowing Ip won't be of any great use.

However ask your friend to look into the Archive section or Trash section. I have also heard that GMail keeps backup copies of your mails, and also that all mails are not deleted immediately, they are retained for a specific period of time. So if your friend can convince GMail support, they might be able to restore the entire thing back.