When using Rename in Microstudio, the file will disappear.
When using the Rename feature in Microstudio 4.004, it will remove the extension of your file, and the file will no longer show in Microstudio.
To fix this, you must find the files that you have renamed, as for example mtu-karaokesong.zip would be renamed to mtu-karaokesong without the extension. You will have to go into Windows Explorer or My Computer to fix the file's extension, so that you can use this file again.
If you have Microstudio 4.004, then you need to download this file to fix this bug,