I just accidentally went over the web.config with my machine key, etc.  Is there any way to get the site back?  Its pretty new so there is nothing to lose really.  Just looking to avoid a reinstall if possible.  Let me know.  Thanks.

Its not a big deal.  I just installed the site today.  There is no content... just a blank 5.0 site.  I will reinstall. I was careless with my procedures because the site wasn't live so to speak... just a pain in the but to go through the install and getting everything in webconfig the way I like it. 

Dear Sebastian Leupold
I already executed all steps as your link guided, I add new user by registration, although my dnn site said register is not success, but I checked it added new user into aspnet_membership table.
After that, I copy Password & PasswordSalt into these fields of host account, but I still cannot logon. My problem is previous machine key is autogenerate, but oneday it has error "you must specify non auto generated key... " Please let me know how can I resolve it?
Thank you so much.