Currently un-localizing an item loses all traces of the content. Tridion doesn't retain any item version history for localized items when they get un-localized.
The question is: what is the problem you want to solve?
Note that these problems may have different solutions, so it is good to know which problem is the most common and urgent to provide a solution for.
Currently un-localizing an item loses all traces of the content. Tridion doesn't retain any item version history for localized items when they get un-localized.