Software

Windows 10 Repair UEFI Boot Partition

Start a command prompt and run:

diskpart

In 'diskpart' run

list disk

Select the disk with Windows installed (if there is one hard disk in the system, its index should be 0):
sel disk 0

Display the list of partitions and volumes on the disk:
list partition
list volume

Usually the UEFI partition will be the hidden 100MB FAT32 partition

Then you can assign a letter to the volume by running: