To recover the defragmentation button feature with the registry

Sometimes we find that the "defragmentation" button in the computer turns gray, is unavailable, and doesn't know how to get it back. In fact, we can use the registry to restore the available status of the defragmentation button.

Locate the file "C:\Windows\Inf\dfrg.inf" (C is your system's letter), right-click and select "Choose Install". Note that to install "dfrg.inf" you need to have the file "Dfrg.msc", "Defrag.exe", "DfrgRes.dll", "DfrgNtfs.exe", "DfrgFat.exe", "Dfrgsnap.dll", " Dfrgui.dll "These files, if the installation process prompts for missing files, you need to insert the system disk, or from another computer to copy the above files to the corresponding directory.