アツコ指示通り実行しました。すべてのコマンドが成功したようです。
DISKPART> select vol 3
Volume 3 is the selected volume.
DISKPART> set id=ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
DiskPart successfully set the partition ID.
DISKPART> gpt attributes=0x0000000000000000
DiskPart successfully assigned the attributes to the selected GPT partition.
DISKPART> assign letter=K
DiskPart successfully assigned the drive letter or mount point.
DISKPART> exit
Leaving DiskPart...
C:\WINDOWS\system32>md K:\Recovery\WindowsRE
C:\WINDOWS\system32>cd /d K:\Recovery\WindowsRE
K:\Recovery\WindowsRE>del c:\windows\system32\recovery\reagent.xml /a
K:\Recovery\WindowsRE>reagentc /disable
REAGENTC.EXE: Windows RE is already disabled.
K:\Recovery\WindowsRE>xcopy /h C:\Windows\System32\Recovery\winre.wim
C:\Windows\System32\Recovery\winre.wim
1 File(s) copied
K:\Recovery\WindowsRE>reagentc /setreimage /path K:\Recovery\WindowsRE /target C:\Windows
Directory set to: \\?\GLOBALROOT\device\harddisk0\partition3\Recovery\WindowsRE
REAGENTC.EXE: Operation Successful.