Hi Ross,
You don't specify what version of Pro you are using.
Some versions back we improved the process of opening a workspace where some tables were missing. Pro would basically be able to ignore these and still generate the workspace as it would look without the missing table(s).
This also remove the need for the Workspace Resolver.
In the earlier versions just a single missing table would bring the loading of the workspace to a stop and so not create any of the maps and other windows, layers, themes and style overrides.
The essense of the workspace should still exist in the workspace file - unless you have saved it after opening it with a number of missing files.
The workspace is basically a text file. If the tables have been moved to a new path, it might be worth opening the workspace file in a text editor and replacing the old paths to the tables with the new path. In this way Pro will easily be able to locate the tables and so be able to open the entire workspace.