Restore a missing TAG(s) to the Tagset?

Unknown said:

Is there a way to restore a missing (deleted) tag element 

Tag elements obey the rules of other elements.  If you delete a tag element you can undo that delete.

Once you exit the drawing you're hosed.

Since we no longer have EDG you can't go into the file and restore the Tag without writing something in MDL.

Unknown said:

You can't go into the file and restore the Tag

Correct: once you exit a DGN file, you've lost the ability to undo edits.

Unknown said:

... without writing something in MDL

None of the development tools provides a magic fix.  None of MDL, VBA or the MicroStationAPI can restore something that is not there.

Unknown said:

Is there a program that would let me select the associated elements of Tagset 1 (old) and 2 (new) and have the Tag values copied to the new Tags?

It's not exactly clear what you're proposing.  If TagSet 1 contains the same tags as TagSet 2, why do they both exist?  But yes, you could write some VBA or MDL code to repair missing tags on an element.

This is one of the main reasons I am a huge fan of initialising Design History on DGN files.

It doesn’t matter if one accidentally deletes or modifies something and they exit the file.

They can restore it at any time :).....

if your on a network you could try to restore previous copy  from explorer ... you'll lose all work done since you lost the tags but make a save as new copy name first you might be able to use as reference to copy changes you might lose...

or ask IT to reinstate an old copy that had the tags from tape backup... but either way you got have a rough idea of when ...