How do I undelete a reference list item? script?

I deleted serveral countries from a reference list because the were duplicates.  For example, New Zealand and NewZealand.  All user records were pointing to New Zealand so I was able to delete NewZealand.

But when I ran a test to live, it failed, giving this error.

The DELETE statement conflicted with the REFERENCE constraint "fk$usr_count$tps_use$68B3DA7C". The conflict occurred in database "ServicedeskDEV", table "dbo.tps_user", column 'usr_country'..

I tried to add back the countries however get an error An entry already exists with the specified name.

Thanks in advance!

Debora