Database Merging / Re-integration I am a SQL Server DBA.  I recently had the misfortune of losing a database due to drive failure. I was able to restore the data but for whatever reason, it stopped at a certain time and not all of the data was restored. 

I restored the database again to a test server only to find and restore ALL of the data but the problem is, I now have to get the rest of the data that did not restore on to the server where it is supposed to be.  Can that be done? 

Given all the primary key contraints and uniqueness of those keys involved, imagine we will have to renumber some of the rows that were affected because those keys have been reused once the database came back up and was operating.
So you attempted to restore the database in production but it didn’t finish? Can you elaborate more, did it finish completely, we’re there any error messages, etc.

Then you were able to successfully restore the database to a test server?

Have you verified if the backup file is good? See this article if not 

https://www.mssqltips.com/sqlservertutorial/113/checking-to-make-sure-a-sql-server-backup-is-useable/

You may want to check that and if ok try to restore in production again.