Hello SweetSeven,
Using that method (same as below), when you restart the computer, any attached VHD files you have will no longer be attached and appear in Computer. You will have to reattach any created VHD file to have it display back in the Computer window again until the next restart.
Virtual Hard Disk - Create and Attach VHD
You could install the free program
VHD Attach, to be able to right click on this or any VHD file to
Attach it and have it displayed in the Computer window as a drive. This will make it easier to reattach the VHD without having to go through Disk Management, but the attached VHD will still be removed after restarting the computer.
If you do not know where you saved the VHD file at when you created it, then you could search for it using
*.vhd to find it.
Hope this helps,
Shawn