My D drive has gone missing

@Gerald229 For better understanding the issue, Are you referring to Azure VM "D" drive(temporary drive) is missing or Data in D(temp) drive is missing? Can you share the screenshot?

Every Azure VM has two disks. A Windows based VM will have a system disk (C:) and the temporary drive (D: by default).
Temp disk is for short term storage. Mostly pagefile.sys. If needed, the drive letter D: can be changed to something else
Use the D: drive as a data drive

Temporary Disk: The temporary storage drive, labeled as the D: drive is not persisted and is not saved in the Windows Azure Blob storage. It is used primarily for the page file and its performance is not guaranteed to be predictable. Management tasks such as a change to the virtual machine size, resets the D: drive. In addition, Windows Azure erases the data on the temporary storage drive when a virtual machine fails over. The D: drive is not recommended for storing any user or system database files, including tempdb.
Temporary disk: https://zcusa.951200.xyz/en-us/azure/virtual-machines/managed-disks-overview#temporary-disk

Additional information: How do I recover my d: drive.

Looking forward for your reply!