While USB flash drives are a convenient and easy way to quickly transfer large quantities of data in a tiny space, the way that they store data can cause them to become easily corrupted. If your computer will not detect the USB flash device or will not allow you to interact with the data stored on the drive, you can use the built-in features of your computer's operating system to attempt to fix the problem before resorting to buying a new drive.
Plug the drive into a USB port that you know is working on a separate computer to make sure that the port itself is not causing the problem. Place the drive back into the original USB port if it remains undetectable on another system.
Open the Start menu and click on "My Computer" to bring up a new window that lists all of the drives connected to your computer. Take note of the letters assigned to the drives connected to your computer. Click on the blue button at the top left end of the window labeled "Map a Network Drive." Click "Continue" if a second window pops up asking for your permission to open the new menu.
Click the "Drive" button at the top of the new window. Select a drive letter from the drop-down menu that is not already in use, such as "Z" or "M." Click on the "Browse" button and locate the USB flash drive that your computer hasn't been detecting. Click on the drive and then click the "OK" button.
Click the "Finish" button to close the window and map the USB flash drive to your computer. Restart the computer and then return to the "My Computer" menu and check to see if the USB flash device is usable. Navigate to the Start menu if the device still isn't working properly, and open Control Panel.
Click the "Administrative Tools" link in the Control Panel menu. Click "Continue." Double-click the "Computer Management" link at the top of the menu. Click the "Disk Management" button at the left side of the window to bring up a list of drives on the computer. Right-click the USB flash drive and choose the "Format" option. Click "Start" and wait for the formatting process to finish. Restart the computer and then attempt to use the USB flash drive again. Note that formatting the USB drive will erase any data contained on it.
If the flash drive remains undetectable by any computer after mapping and formatting, the problem is a mechanical defect and the unit will need to be replaced.
Formatting the drive will completely erase any data that was stored on it.