The search for the cause
So, first you need to check that it is faulty. To do this, insert the flash drive into the USB port and check whether flashing light, located on the flash drive. If the indicator is blinking, the problem with the USB connector and the flash drive is not. In this case, most likely, the reason lies in the failure of the operating system of your personal computer. If the led is not blinking, then the faulty flash card or USB connector.
The problem with the USB connector
If you insert a USB flash drive into the USB port on the front panel of the system unit, you should check whether you have connected the power Flex cable of this connector. Also often there are times when ports on the front panel is just not enough power. To check this, you need to enable the flash drive into the USB ports at the back. If this does not work, you should make sure whether there is enough power the rear USB ports. Usually they are heavily Laden with you connect various devices like mouse, keyboard, printers, scanners, etc., Disable some of these devices and recheck performance.
If this procedure fails, it means that the reason is likely the faulty stick. This can be checked by connecting it to another PC or laptop. If other computers do not show the connecting stick, then you should consider repairing or replacing the stick.
The fault of the OS
If it turns out that the flash drive and the USB connector is workable, the problem is likely in the settings of the operating system. For example, can be turned off USB support in the BIOS. If not, then when you connect the flash drive, you should see the error message about the impossibility of recognition of the USB device. The reasons for this are. One of the possible – when the operating system assigns a drive letter already mapped drive. Then you only have to change the drive letter of the flash drive under "disk Management" control panel, so the conflict was resolved.
Another reason may be outdated or missing drivers stick. Also consider updating your motherboard drivers. There may be one more reason that the computer does not see the stick, is the presence of viruses in the computer. Then you need to scan your computer for viruses, and then remove all infected files. By the way, one of the reasons for the broken stick also can be the incompatibility of the file system of the flash drive and the computer. It is better to format the flash drive to FAT32 or NTFS. This can help to resolve the issue.