I have 2 drives. When I was switching from a HDD drive to an SSD drive a "boot menu" with 2 Windows systems (and one of them not working) popped up while booting Windows.
Today I wanted to delete a partition left by Ubuntu on my HDD and resize my "Stuff" partition. I also saw a "System" partition so I thought it's that stupid thing in the "boot menu". Later I wanted to play some games on Windows but it wasn't booting. I checked the BIOS boot menu and "UEFI Windows Boot Manager" (or something like that) was missing.
I can't get the Windows 10 installer since this is my only computer and my second USB stick is filled with important stuff.
The only thing left is my bootable Linux Mint USB stick. I damaged my installation and don't know what to do.
EDIT: I found my Windows installation USB stick, but after plugging it in it displays a message about BOOTMGR being corrupt.
