This 30-day delay is intentional. It’s a security safeguard designed to protect users in case someone else tries to hijack their account by changing recovery info. The wait gives the rightful owner time to notice and stop unauthorized changes.
Unfortunately, this policy cannot be bypassed. Microsoft explains it further here.
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For the birthday info, once you regained access back, you can update it via https://account.live.com > Your info.
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Since you were going to reset it anyway, you can do a clean install. That shouldn't require bitlocker key. However, you won't be able to log back into the same Microsoft account after that as your security info is pending. So you will need to set it up with a different Microsoft account for now, disable bitlocker right away after that, then wait 30 days and link your Microsoft account back.
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To perform a clean installation of Windows 11 using the Windows Media Creation Tool. You do need to get access to another computer so you can download the Windows installation files into a flash drive, then use the flash drive to help your computer. Hopefully you have a spare computer, or you can have friend or family help you.
The following steps should be done on a working Windows computer:
Download the Windows Media Creation Tool from Microsoft's official website. https://www.microsoft.com/software-download/windows11 click on the "download now" button under "Create Windows 11 Installation Media"
Run the tool and select "Create installation media for another PC."
Choose "USB flash drive" as the media to use for the installation and select "Next."
Connect a USB flash drive with at least 8 GB of free space to your computer.
Select the USB flash drive you want to use, and then select "Next."
The tool will then download the required files and create the installation media.
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Now these steps will be done on your problematic computer:
Go to the computer's BIOS boot menu to have it boot from the USB drive.
Follow the on-screen instructions to install Windows 11, making sure to choose "Custom install" and select the option to delete all existing partitions.
Once the installation is complete, you'll have a clean installation of Windows 11 on your computer.