What happens as i reinstall windows?

What PC have you got, as you first need to backup all your personal files from the PC and then do a Clean Install of the OS. Give us more details as certain laptops/desktops need certain drivers to be able to completely format the M.2 boot drive and continue the OS installation after a compete format of the boot drive.

To do a complete windows backup of your current OS, you first need to create a restore point on your boot drive (C:) as without that your backup will not be successful, after and to do the backup, you need to go into Control Panel >Backup and Restore (Windows 7) to back your OS up, as that will do an exact copy of your operating system and all its files, its also advisable to Create a recovery USB drive:

• To create a recovery drive in Windows 10 or 11 do this:
• 1. In the search box next to the Start Windows logo Start button, search for Create a recovery drive and then select it. You might be asked to enter an admin password or confirm your choice.
• 3. When the tool opens, make sure Back up system files to the recovery drive is selected and then select Next.
• 4. Connect a USB drive to your PC, select it, and then select Next.
• 5. Select Create. Many files need to be copied to the recovery drive, so this might take a while.

Any specific need for why you are reinstalling windows?

Personally, whenever I get a new laptop I do the following:

1. Collect all drivers for all devices and back it up.
2. Take an image of all partitions needed to restore.
3. Install windows wiping clean everything from a boot up USB created out of windows downloaded from microsoft site to keep bloatware to a minimum.
4. Post install I go to Acer site for my laptop and download the utility software like nitro sense and install it.

Windows key is retrieved from BIOS and so windows is already activated. But since i I use pro, i upgrade it with my Pro key.

And then regular process… updating the Group Policy to my personalizations and privacy requirements.