According to these upgrade instructions from Testlink, it should only be necessary to use phpMyAdmin to export/import data from the old version database to the new one.
You can download Test Link 1.9.5 installer for Windows platform from the link below, but please note that this is a quite old version and that it may be affected with many security issues solved since it was released. We highly recommend you to download the latest Test Link installer from https://bitnami.com/stack/testlink/installer and migrate your current data to the new one.
Download link for the Bitnami Test Link Stack version 1.9.5-0 for Windows
Please let us know any other question you may have.