Difference between 'Data Not Available' and 'Record Deleted' error messages when accessing a record

Understanding the Two Error Messages

The key difference between these two errors is whether the record ID still exists anywhere in Salesforce's system.

Record Deleted

Record Deleted means the record was deleted by a user and is currently in the Recycle Bin, or has been removed from the Recycle Bin but has not yet been fully purged from Salesforce's backend systems. In this case, the record ID still exists in the system.
The user who deleted the record can recover it from the Recycle Bin within 15 days of deletion by navigating to the Recycle Bin from the App Launcher.
Real-life example: If a support agent deleted an Account record 3 days ago, the message will read "Record Deleted" because the record remains in the Recycle Bin.

Data Not Available

Data Not Available means the record cannot be found in any system state. This occurs when the record has been permanently purged (past the 15-day Recycle Bin window), when a system error occurred, or when the record ID never existed.
If you are certain the record was not deleted, contact Salesforce Support with the record ID and the timestamp when the error first appeared.
Real-life example: If the same Account record was deleted 20 days ago, it will show "Data Not Available" because the 15-day Recycle Bin purge window has passed.