To diagnose and resolve message loss in Kafka streams, we should first check the offsets. It is essential to determine how many messages are in the topic and how much the offset has advanced. 

Next, we need to examine the replication factor, as ensuring sufficient replication is crucial for protecting against data loss. We must also verify acknowledgments to confirm that messages are being acknowledged and not lost during transit.

Additionally, we can review Kafka's internal consumer logs. Utilizing Kafka's built-in tools will help us inspect whether the data is present in the streams. We should also check Kafka logs for any failure messages, as these can indicate issues with message processing or delivery.

By examining offsets, replication factors, acknowledgments, and logs, we can effectively diagnose and resolve message loss in Kafka streams.