Hard Drive Disappeared

[CroyBoyd]

My Gigabyte laptop has an internal C ssd drive with the Windows operating system and an internal D drive for storage, but the D drive just randomly disappeared. Nothing I have downloaded would have triggered this and it won't appear in the partition settings of the computer. How do I find it? All apps that were on it will no longer open.

I have tried restarting and system restoring the computer, but it says that the system restores fail.

Laptop: https://www.newegg.com/Product/Product.aspx?Item=N82E16834233113

 

[RolandJS]

I'm not understanding, your external HD is a storage drive, however, apps won't open -- did you install much of your 3rd party programs onto this storage HD?
On a related note, have you been making OS partition and Data & Apps partition backups onto other reliable external media?