I have lost all my contacts in ver: 12.0.7816

I have used Teamviewer for about 10 years. I use it non-commercial, just with family, about 12 contacts. With all the upgrading, changes in a feature, I have lost my contacts. Some of these would be just about impossible to re-create them. The original email was created a long time ago and I have no access to it. I have tried to change username and password but not sure if it ever went through. Anyone have any ideas? Thanks, RogMann