We have a newly created 2.0 account where one of our business units stopped writing to the parent sendlog. In order to get the process to work properly, we were advised to delete various sendlog file(s) that were inadvertently created in that business unit(filters were being run against these rogue "sendlogs" for reporting.) Is there a way to recover that sendlog(s) data so we can append the parent sendlog file?
If you deleted records from these individual Data Extensions, you may not have many options open to you, other than see if you can assemble what would have been in the data extensions based on the _Sent data view and other Data Extensions from which you were logging values to these Send Logs.
If you simply dropped the Data Extensions in the child Business Units, you would need to get back in touch with Salesforce Support to have the Data Extensions you deleted reinstated. Data Extensions are only soft-deleted and Support have access to a utility to "undelete" them.
Once reinstated, ensure your Enterprise Send Log Data Extension is in a Shared Folder and create and execute Query Activities in each of the Business Units that append to the Enterprise Send Log.
Finally, re-delete all the child Business Unit send log Data Extensions.