lost d drive when installed new c drive

You haven’t said what you have tried to recover the drive, but here are two things that may help: 1. Go to Control Panel > All Control Panel Items > Folder Options > View Tab, scroll down and confirm that there is a tick in ‘Show drive letters’. 2. Right-click Computer > Manage > Storage > Disk Management, then right-click the disk’s graphic icon (or unallocated space) and change the drive letter to one nearer the end of the alphabet. If it doesn’t have a letter, try to assign one to it.