Private Declare Function GetLogicalDriveStrings Lib "kernel32.dll" Alias "GetLogicalDriveStringsA" (ByVal nBufferLength As Long, ByVal lpBuffer As String) As Long

Private Sub Test()
    Dim sDrives As String, iLenght As Long, xDrive As Variant
    
    sDrives = String(255, vbNullChar)
    iLenght = GetLogicalDriveStrings(Len(sDrives), sDrives)
    sDrives = Left(sDrives, iLenght - 1)
    
    For Each xDrive In Split(sDrives, vbNullChar)
        MsgBox xDrive
    Next
End Sub