IIS7 manager password problems after Windows administrator password change

Our network administrator recently left and, until we get another one, I'm filling in trying to keep the servers running :o

I changed the administrator password for the server (Windows Server 2008), and since then if I try to manage IIS through IIS Manager I get prompted for a username and password and I can't access it. If I change the server administrator password back to the original then I can connect again. Does anyone have any ideas please?

Failed to connect

There was an error when trying to connect. Do you want to retype your credentials and try again?

Details:

Logon failure: unknown user name or bad password. (Exception from HRESULT: 0x8007052E)

Yes No

In case anyone comes across this, it was to do with shared configuration. To fix this, I took the following steps:

1. Change the administrator password back to the old one
2. Open IIS manager
3. Change administrator password back to new password
4. Set the password in shared configuration

I believe it can also be fixed using appcmd, but I never worked out how.