The passwords are not stored in the files. I don't believe there is a way to recover them. Did you try"Admin" as user name with a blank password?
The passwords are stored in the files, but are encrypted in current versions. Go back enough versions and they were not encrypted and quite extractable from a file--that's why they are now encrypted.
There used to be "cracker" utilities that would extract the passwords. Current versions go the other route and insert a new account name and password into the file. These are "use at your own risk" utilities as they modify the file itself to gain access.