How can I use avast premier license after reinstall windows10?

Hi everybody.
I had a complete PC break after Win update. Microsoft told me to reinstall windows. I have perpformed it. The name of my PC somehow changed and I lost all the programs. How can I to reinstall and to use my Avast Premier and Avast Cleanup further? There are no Avast contacts at all in their Russian site and there is no the form to make a contact with them. Please help!

https://www.avast.com/resend-license-paid.php (Resend paid license)