From the user interface you can run the BOM Where Used Report and have it return any Inactive Routings.  (Run the report where "Active is equal to No".

If you have access to the database to run a query, the following will provide you with the list of Child Routings that are inactive and any Parent Routing that they are associated with.

select ChildRouting.RoutingId as 'ChildRoutingID',

          ChildRouting.VersionId as 'ChildVersion',

          ChildRouting.Active as 'ChildActive',

          ParentRouting.RoutingId as 'ParentRoutingID',

          ParentRouting.versionid as 'ParentVersion'

from tmfRoutDetl_HAI ParentDetail with (nolock)

join tmfRoutHead_HAI ParentRouting with (nolock)

         on ParentDetail.RoutingKey = ParentRouting.RoutingKey

join tmfRoutHead_HAI ChildRouting with (nolock)

         on ChildRouting.RoutingKey = ParentDetail.MatRoutKey

WHERE ChildRouting.Active = 0

Thanks for you feedback.