Talking with a colleague of mine today, I was explaining how sites in SharePoint are lost once deleted. Meaning, a deleted site will not be saved to the recycle bin like a list/item/document would be for example. This is the expected behavior out-of-the-box.
Now, you could use an event handler to override the WebDeleting method
and either prevent the user to delete the site or make a copy of the site and its content somewhere so that it can be retrieved if it is ever needed.
A solution was already created which does just that called ‘MSIT Site Delete Capture 1.0.’ See here for more information.
I also wanted to share a good video on event handler by Ted Pattison that I thought was pretty good. Watch the video here.