user35003: I have an Arduino micro for some time and everything always worked well. Today, when I was uploading a code on this board using Arduino IDE, I accidentally started the Arduino Board update and the upload failed. After a while I retried again and again and again but upload always failed. Now my PC doesn't recognize my board and, looking at Windows Device Manager, when I connect my board, appears this screen:

What should I do? Do I have to reflash bootloader?

user31120: So I was facing this issue for the past few hours and this is how I managed to get it to work. 
After reading similar issues on knockoff NANOS,  I downloaded and installed this as many knockoff NANOS uses a different Serial CHIPSET.
After that, on the IDE side, just press compile to ensure your code is good to go. And then when you hit upload, wait for it to finish compiling and the second it says UPLOADING, hit the reset button. It should upload now and be available in your COM port.

user54057: I had this issue a while back and in order to fix it as suggested above I had to re flash the boot loader using a 2nd Arduino as an ISP. I used this page as a guide:
https://schou.dk/linux/arduino/isp/
Before connecting the wiring I first updated the UNO with the "ArduinoISP" Sketch, connected the wiring, then flashed the boot loader.

35003: <p>I have an Arduino micro for some time and everything always worked well. Today, when I was uploading a code on this board using Arduino IDE, I accidentally started the Arduino Board update and the upload failed. After a while I retried again and again and again but upload always failed. Now my PC doesn't recognize my board and, looking at <em>Windows Device Manager</em>, when I connect my board, appears this screen:</p>

<p><a href="https://i.stack.imgur.com/2Rb2y.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2Rb2y.png" alt="Unknown USB device"></a></p>

<p>What should I do? Do I have to reflash bootloader?</p>
 31120: <p>So I was facing this issue for the past few hours and this is how I managed to get it to work. 
After reading similar issues on knockoff NANOS,  <a href="http://www.wch.cn/download/CH341SER_EXE.html" rel="nofollow noreferrer">I downloaded and installed this as many knockoff NANOS uses a different Serial CHIPSET.</a></p>

<p>After that, on the IDE side, just press compile to ensure your code is good to go. And then when you hit upload, wait for it to finish compiling and the second it says UPLOADING, hit the reset button. It should upload now and be available in your COM port.</p>
 54057: <p>I had this issue a while back and in order to fix it as suggested above I had to re flash the boot loader using a 2nd Arduino as an ISP. I used this page as a guide:</p>

<p><a href="https://schou.dk/linux/arduino/isp/" rel="nofollow noreferrer">https://schou.dk/linux/arduino/isp/</a></p>

<p>Before connecting the wiring I first updated the UNO with the "ArduinoISP" Sketch, connected the wiring, then flashed the boot loader.</p>
