Disk Drive Failures and Data Loss from Windows PC

My Windows PC suddenly stopped recognizing my secondary internal hard drive, and when I check Disk Management, the drive shows as unallocated space or raw format, even though it contains years of critical personal and work files that I desperately need to recover. I've already tried running chkdsk, updating storage drivers, and connecting the drive via a different SATA port and external enclosure, but the system either fails to access the partition or prompts me to format the disk before use, and I'm worried about permanent data loss, so I would greatly appreciate any advice on safe recovery methods, partition table repairs, or reliable software tools that won't further damage the drive or overwrite my existing files.