If there is nothing wrong with the system, the power supply of the USB interface is insufficient, which may be caused by too many peripherals connected to the USB interface. It is recommended to use a charged USBHUB or USB to PS/2 adapter. It is also possible that Windows turns on the power-saving mode by default, resulting in insufficient power supply to the USB interface and intermittent failure of the USB interface. Right-click my computer/properties/hardware/device manager, double-click "universal serial bus controller" to go to several "USB root hubs", double-click any one to open the properties dialog box, switch to the "Power Management" tab, uncheck the check box before "Allow the computer to turn off this device to save power", click OK to return, and then modify the properties of each USB root hub in turn and restart the computer. USB devices can resume stable operation, and the frequency should be set as low as possible.

If there is no displayed drive letter, the solution: right-click My Computer/Management/Storage/Disk Management, then right-click the icon of removable disk, click the option of "Change Drive and Path" in the shortcut menu, click the "Add" button in the subsequent interface, then select "Assign Drive Letter", select the appropriate drive letter from the drop-down list next to this option, and click OK. Finally, turn on the computer and you will see the drive letter of the mobile hard disk.

It is also possible:

1. There is something wrong with your machine interface. The solution is to change the interface.

2. It may be that your computer system is incompatible with your machine, which makes the computer unrecognizable! The front of some computers is caused by insufficient power supply, so just plug it in the back.