@jhoward
1. How was the "/etc/ambari-server/conf/ambari.properties" file got deleted?
2. Do you have a backup of this file "amabri.properties" to use?
3. Ambari stores all the cluster informations inside it's Database. So if your Database is not dropped (lost), you can try using a dummy "ambari.properties" of same version from any of your other working cluster by just changing the JDBC settings to point to your correct ambari DB host/port and with DB credentials.
The DB settings for ambari can be found from following command (in any of working ambari cluster) and then you can try to place those properties with correct Database values in your problematic ambari
# grep 'jdbc' /etc/ambari-server/conf/ambari.properties
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