Identify your target drive number by looking at the size column (e.g., Disk 0 is usually the primary internal hard drive or SSD).
Diskpart is a "destructive" tool. Using the clean command completely wipes the selected drive, removing all partitions and data. There is no "Undo" button. Please back up any important data before proceeding.
Make sure the drive is connected properly and, if using a NVMe SSD, that your BIOS is set to AHCI/NVMe mode.
Is your motherboard firmware set to or Legacy BIOS mode? Share public link