What version of Cloudera Manager are you using? In recent releases, it should not be possible to have this sort of thing happen unless your database is indeed without any information.
Go to the following directory:
Next, look at the db.properties file.
Make sure it is configured properly with your correct database host, port, etc.
If not, you can also look at other db.properties files in the directory to see if any of them may contain the correct information.
If you are unsure, feel free to share the information here (redcacting your password if necessary)