Thanks for contributing to our forum. Hopefully most buyers would remember a purchase that was lost or damaged during shipping, but I certainly understand how that may be some circumstances such as those you have mentioned that could make it difficult (or impossible) to get the buyer claim form that is typically required for the processing of a claim.
Shipsurance, the company who underwrites the shipping insurance policies we offer, does have buyer claim forms available in several different languages so, if this particular buyer is located outside of the US, I recommend checking with Shipsurance to see if they have a form in the buyer's native language.
If the buyer does not respond to your requests to complete the required form, I also recommend contacting Shipsurance for advice on how to proceed from there using the contact information on the following page of their website:
I hope this helps.