Hello Adil365,
In regards with this post, the pieces of information below are applicable for all entities, not only for marketing lists.
In terms of the technical background of this issue, marketing lists records, those which had been there from years in Legacy client under Marketing->Marketing list and the only way to trace them back is via Audit.
If your organization is on premises you can try something similar with this on SQL level:
select * from listbase where listname like '%your_marketing_list_name%'
together with something similar with the replies to this particular post:
https://community.dynamics.com/crm/f/microsoft-dynamics-crm-forum/53847/where-would-i-find-in-crm-4-0-marketing-lists-members-sql-table/97653
As the design of our tables did not change too much since 2011, that should be ok in terms of tracking down that list.
If on the other hand the organization is online, Web API might be able to help, you have below the entity type to help you understand the filtering criteria for those:
https://docs.microsoft.com/en-us/dynamics365/customer-engagement/web-api/list?view=dynamics-ce-odata-9
The filtered list does not have an Web API does not have a correspondent in there.
The only way you can try to understand what happened with those lists is to verify the modified on and modify by, which are part of the results of the queries above, if they will return any result.
In terms of possible reasons for the behaviour:
- it can have a relationship with an organization reset/restore
- it might be an automatic process, like for example a bulk delete performed on the incorrect criteria
- or a manual delete
Without an entry for the list record in the query provided above there's no way to understand why the list does not exist anymore, unless you have some tracking in an external system or something similar, but out of the box, only Audit if it is enabled might help.
In terms of how to recover them, it depends, an organization restore, keeping in mind that organization restore will also remove the records created between the time of your last backup and the time of the restore unless you have a way to trace those and to export them prior to the restore in order to import them back after the restore.
On the other hand, if the record exists and it is only disabled, this would be the perfect situation, as the only thing you need to do is to reactivate it, but the chances are small, based on the description above.
Thank you,
Madalina Toma
Microsoft D365 CE Support