Help! My Windows Partition Disappeared from GRUB and Boot Manager

Another idea is to run `sudo os-prober` in your terminal. If it doesn't find anything, try editing your GRUB configuration file by using `sudoedit /etc/default/grub`. Un-comment or add this line: `GRUB_DISABLE_OS_PROBER=false`, and then run `sudo update-grub`. This should help GRUB to detect your Windows installation.

First, you should check if your Windows partition is still there. If it exists, you can try using the boot repair tool that comes with Linux Mint or by running `sudo update-grub` in your terminal. If it doesn’t automatically show Windows Boot Manager, you might need to add it manually by selecting "Boot from file" in your UEFI menu and locating the file at /EFI/Microsoft/Boot/bootmgfw.efi. If that does not work, a manual boot entry will be necessary.