Arduino IDE cannot recognize clone Arduino MEGA 2560 (Windows 10)

I have about the same chinese board over here, same color, same layout, apart from the chip that does the conversion to USB, so it is not identical.

The issue is that at the beginning it was working just fine! No problem at all, and suddenly not recognized! What is this...

OK, well it is a tossup between a hardware problem (bad connection, board fault) and Windoze ten being - well, Windoze!

The most serious approach I can offer is to find a PC running - or install - Linux; I find Mint singularly usable and it does not fart around with this sort of thing like Windoze. There is one (fully documented) once-only configuration trick to using the USB port for an Arduino but that is the end of it.

I suppose you did try it on another Windoze box somewhere?

I have access only to Windows 10. Ok I will try it to linux...

Not surprising given the push to deprecate all earlier versions including the more functional Win7.

I mean did you try it on another PC running Win10?

No, I haven't!