If it isn't detected on any PC, it's a clear warranty issue. Get a new one before it fails totally!
Be sure to get your data safely off and delete everything on it before you give it back.
i have bought a sandisk 3.0 usb recently.In the first 2 or 3 days it was working fine but after it started detection issues. It will never get detected by any pc and when i try after a day or two it will get detected for once and will show all the data i have stored on it no copying issues and also the size of the usb is still the same no change with respect to size

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