Hi rhys mullen,
I'm not sure what methods you have tried, I will suggest you this one and hope it helps, it's performing an In-place upgrade.
Disclaimer: Let’s try performing an in-place install or in-place upgrade which will refresh your Windows files and operating system without removing files or applications. That being said, we always recommend that if you have important data, you should back it up before making large system changes. If you want to back up your data first, please do so. Once you are done backing up, you can follow the steps in the following guides: How to run In-place upgrade in Windows 11 - Microsoft Community
After doing so, please try install applications from Microsoft Store again.
If you have further information, please feel free to let me know.