Answer:
Cause: If you have a disk that does not appear in File Explorer and is shown in Disk Management as Uninitialized, it may be because the disk does not have a valid disk signature. Basically, this means that it has never been initialized or formatted, or that the drive format has been damaged in some way.
It is also possible that the disk has hardware problems or problems connecting, but we will get to that in some paragraphs.
Solution: If the unit is completely new and should only be initialized, erasing the data it contains, the solution is easy: see Initialize new disks (Initialize new disks). However, there are many possibilities that you have already tried this and that it has not worked. Or maybe you have a disk full of important files and you don't want to erase it by initializing it.
There are a number of reasons why a disk may fail or that it did not have to be initially started, with a common reason why the disk is failing. There are many things that can be done to correct a disk error, but here are some steps to see if we get them to work again. If the disc works after performing one of these steps, do not worry about the following; just relax, celebrate it and, maybe, update the backups.
Examine the disk in Disk Management. If Disconnected appears as shown here, try to right-click on it and select Connected.
The disk appears as disconnected
If the disk appears in Disk Management as Connected and has a main partition that appears as Correct, as shown here, it is a good sign.
The disc is shown as connected with a correct volume
If the partition has a file system, but no drive letter (for example, E :), see Change a drive letter (Change a drive letter) to add a drive letter manually.
If you don't have a file system (NTFS, ReFS, FAT32 or exFAT) and you know the disk is empty, right-click on the partition and select Format. When formatting a disk, all the data it contains is erased, so don't do it if you are trying to recover files from the disk; instead, go to the next step.
If you have an external disk, disconnect it and reconnect it, and then select Action> Re-examine the disks.
Turn off your PC, disable the external hard drive (if it is an external drive with a power cable), and then reactivate your PC and disk. To deactivate your Windows 10 PC, select the Start button, then the power button, and then select Shut down.
Plug the disk into another USB port that you can find directly on your PC (not in a hub). Sometimes, USB disks do not have enough power from some ports or have other problems with certain ports. This is especially common with USB hubs, but sometimes there are differences between the ports of a computer, so you can try different ports, in case we have.
Try another cable. It might seem crazy, but the cables fail a lot, so you can try using another cable to connect the disk. If you have an internal disk on a desktop computer, you will probably need to turn off your PC before changing cables; Consult your PC manual for more information.
Composed by Device Manager to see if there are problems. Press and hold the Start button (or right-click on it), and then select Device Manager from the context menu. Search for devices with an exclamation point next to it or other problems, double-click on the device, and then read its status.
