Hi, I am Dhanam, Independent Advisor here to work with you on this issue.
I know this has been difficult for you, Rest assured, I'm going to do my best to help you.
Open Settings.
Click on Apps.
Click on Apps & Features.
Select the ROBLOX from the list.
Click the Advanced Options link.
Click the Reset button.
Click the Reset button again to confirm.
Restart your device.
This is a public user-to-user support forum. I'm a user like you helping other users. I do not work for Microsoft and cannot access any user accounts.
I hope this can help you. If this still can't solve your problem, just let me know and I'll do my best to try to help you.
Regards,
Dhanam,
Independent Advisor.