Hi TheBoysOfWALES,
Welcome to the Microsoft Community.
It sounds like you lost all bluestacks backups and HDD after a reinstallation of your Windows 11 Pro Insider Preview. Sorry to hear this. I understand the frustration when the thing won’t work the way we want. Any corruption to the Master Boot Record (MBR) can lead to a hard drive crash thus resulting in file loss.
In this case, it is advised to stop any operation on your Windows, and contact bluestacks or a professional data recovery institution to investigate the possibility of restoring your lost files.
I hope this helps, and feel free to reach back if you need further assistance.
Best regards
| Lynn Sun Microsoft Community Support Specialist
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