Lenovo X1 Carbon boots to a 2100 error

When you get the 2100 error, it’s usually an issue with the drive itself or a drive stuck in BSY status - in other words, software is not likely to help. If it’s a BSY issue and you know what you are doing(!!!), you need to get into the drive’s diagnostic mode and refresh the controller to kick it out of the BSY mode so it can register again. DO NOT TRY THIS IF YOU DO NOT KNOW HOW; ONE CHARACTER ERROR CAN BE FATAL!

Since the drive isn’t showing in software, something is seriously wrong with the drive, and it has a physical issue or a mapping issue that requires professional assistance since end user software tools aren’t helping - you’re going to pay a lot for this :-(. Hopefully you have a backup or you can recreate the data!

If you do not have a backup, you had to learn the hard way sadly.

It's usually lose connection and in case of SSD it's baad connector. Get it replaced in repair shop and thank me later. No other solution.