If you have a cheap or unbranded USB flash drive that suddenly shows "0 bytes," won't format, or has disappeared from File Explorer, you’ve likely encountered a controller firmware failure.
The good news? If your drive uses an ASolid controller (common in budget drives from AliExpress, Amazon, or generic brands), the ASolid USB MPTOOL (Mass Production Tool) can bring it back to life. asolid usb mptool verified
Warning: This tool is powerful. It low-level formats your drive and permanently erases all data. Use it only to repair dead drives or restore them to factory settings. If you have a cheap or unbranded USB
Assuming you have found a verified version (we will discuss where to look below), here is the exact workflow. Warning: This tool is powerful
ASolid Technology Co., Ltd., formerly known as Alcor Micro, is a Taiwanese semiconductor company that designs high-performance controller chips for USB flash drives, card readers, and SSDs. If you have a budget-friendly or mid-range USB drive from brands like Kingston, Silicon Power, PNY, or Transcend, there is a high probability it runs on an ASolid chip (e.g., AU6989, AU6990, AU89102, or AU87101).
If your drive is completely dead (not detected at all), you must enter "Mask ROM Mode."
Once the progress bar hits 100% and turns green: