I modified a lot of options in IIS, and would like to reset its settings to default.
I already tried installing/reinstalling it. After the reinstall, it still had the site I created. It was still breaking on the setting I made to the DefaultWebSite.
People suggested uninstalling Windows Process Activation Service first, but it seems like it wasn't installed anyway, so I can't really uninstall it.
How can I reset this installation of IIS back to an out-of-the-box state?
This link has some useful suggestions: http://forums.iis.net/t/1085990.aspx
It depends on where you have the config settings stored. By default IIS7 will have all of it's configuration settings stored in a file called "ApplicationHost.Config". If you have delegation configured then you will see site/app related config settings getting written to web.config file for the site/app. With IIS7 on vista there is an automatica backup file for master configuration is created. This file is called "application.config.backup" and it resides inside "C:\Windows\System32\inetsrv\config" You could rename this file to applicationHost.config and replace it with the applicationHost.config inside the config folder. IIS7 on server release will have better configuration back up story, but for now I recommend using APPCMD to backup/restore your configuration on regualr basis. Example: APPCMD ADD BACK "MYBACKUP" Another option (really the last option) is to uninstall/reinstall IIS along with WPAS (Windows Process activation service).
There is one way that I have used my self. Go to Control Panel\Programs\Turn Windows features on or off then uninstall IIS and all of its components completely. I restart windows but I'm not sure if it's required or not. Then install it again from the same path.
What worked for me was going to the article someone else had already mentioned, but keying on this piece:
application.config.backup is not created by automatic backup. The backup files are in %systemdrive%\inetpub\history directory. Automatic backup is also a Vista SP1 and above feature. More information can be found in this blog post, http://blogs.iis.net/bills/archive/2008/03/24/how-to-backup-restore-iis7-configuration.aspx
I was able to find backups of my settings from when I had first installed IIS, and just copy and replace the files in the inetsrv\config directory.
You need to uninstall IIS (Internet Information Services) but the key thing here is to make sure you uninstall the Windows Process Activation Service or otherwise your ApplicationHost.config will be still around. When you uninstall WAS then your configuration will be cleaned up and you will truly start with a fresh new IIS (and all data/configuration will be lost).
Resetting IIS
a. From the Start menu, choose All Programs, and then choose Accessories. b. Right-click Command Prompt, and then choose Run as administrator.
At the command prompt, type the following command to change to the Microsoft.NET\Framework64\v4.0.30319 folder, and then press Enter.
cd\Windows\Microsoft.NET\Framework64\v4.0.30319
At the command prompt, type the following command, and then press Enter.
aspnet_regiis.exe -iru
At the command prompt, type the following command, and then press Enter. iisreset
There are automatic backup under %systemdrive%\inetpub\history but it may not help much if you already made lots of changes.
http://blogs.iis.net/bills/archive/2008/03/24/how-to-backup-restore-iis7-configuration.aspx
You will have to regularly back up manually using appcmd.
If you try to reinstall IIS, please first uninstall IIS and WAS via Add/Remove Programs, and then delete all existing files under C:\inetpub and C:\Windows\system32\inetsrv directories. Then you can install again cleanly.
WARN: beginners on IIS are not recommended to execute the steps above without a full backup of the system. The steps should be executed with caution and good understanding of IIS. If you are not capable of or you have doubt, make sure you open a support case with Microsoft via http://support.microsoft.com and consult.
Source: Stackoverflow.com