Hi SnowElf. Since you have made a major change to your operating system, you should create a new backup and not try to reactivate your old one.
If you are needing to restore your data, then you can browse to the backup location and manually copy and paste your data back to your computer. If you are needing to restore your data, that means you may have formatted your computer when you upgraded your OS, and since you have reinstalled Windows and using a different operating system, you probably will not be able to do an automated restore as your Windows paths may now be different. If you try to do an automated restore, you will probably not see most of your data where you would expect to see them.
After you have manually restored your data, you can download the latest version of WD Anywhere Backup from the restricted downloads section of the Western Digital registration page and create a new backup plan.
Link: How can I move or copy files from one hard drive to another in Windows?
Western Digital Product Registration : https://websupport.wdc.com/registration/
