Yasin, What you need to do is to put up a page so that members logging in can see a notice that a server crash; white lies are good, resulted in the lost of the site and you are asking for them to send you an email so you can notifiy them when you can get the site back up and running.  Don't just walk away from all that work, you might can salvage your member list.  Take advantage of Andrew's offer for help in getting your site back on line.