This is for sites and subsites (not site collections). Let’s say the site collection home page is http://home.company.com/default.aspx and you want to protect the site you created for the Engineering department at http://home.company.com/engineering/default.aspx. Maybe you’ve spent a month building the site – you’ve customized pages, created special library views, used audience targeting and even thrown in some pretty complex permissions to protect confidential documents from too many eyes.
You decide to give someone else Full Control of the site so they can help you manage permissions. That’s okay, but one day, that person – who really meant to delete another subsite – accidentally deletes your site! Yikes!!
Unfortunately, sites that are deleted cannot be recovered from the site or site collection Recycle Bin (like documents, pages and lists can be recovered). Yes, there may be a backup somewhere and someone can probably get it restored for you but that can take days and in the meantime, you’ve lost all of your work and you may not be able to get your site restored at all.
So here’s a really easy tip to keep that from happening in the first place…
Sites with subsites CANNOT be deleted. So all you need to do is create a subsite underneath the Engineering site and only give yourself permission to it (no one else). Use a blank site template and don’t put any content there. It will take up very little room in the database and it will prevent someone from accidentally deleting your site.
Here is the MS link on how to do site restores in the unfortunate circumstance where you do delete your site !!!