Erroro code 0xE001F90F: The product does not exist

I have had to reinstall AVG and I am getting this message. I have recently had a WINDOWS 10 upgrade & anti virus stopped updating.  I have tried reinstalling and I am getting this message. So at present my PC isn't secure. Please help !!

Quentin,
I understand this must be upsetting. I will help you to fix it.
To resolve the issue please follow the steps provided in this article : http://support.avg.com/SupportArticleView?urlname=How-to-troubleshoot-issues-after-upgrade-to-the-latest-AVG-antivirus-product

Note : Please run the AVG Clear first and then the AVG Remover

Once uninstalled, please reinstall the AVG AVG Internet Security from http://support.avg.com/SupportArticleView?urlname=Download-and-install-AVG-AntiVirus-Internet-Security-or-Premium-Security

Quentin,
I understand this must be upsetting. I will help you to fix it.
To resolve the issue please follow the steps provided in this article : http://support.avg.com/SupportArticleView?urlname=How-to-troubleshoot-issues-after-upgrade-to-the-latest-AVG-antivirus-product

Note : Please run the AVG Clear first and then the AVG Remover

Once uninstalled, please reinstall the AVG AVG Internet Security from http://support.avg.com/SupportArticleView?urlname=Download-and-install-AVG-AntiVirus-Internet-Security-or-Premium-Security