I have downloaded and used Arduino IDE v1.8.4 from official site (needs no install) for windows10, and connected my random board with a ch340, but it's LED is only blinking and I can't select the port (ie. it's grayed).
I did test all USB ports and restarted my laptop but that didn't work!
I tried to install 1.6.9 IDE that I had before, but again the port option is unselectable!
This is my board: http://uupload.ir/files/xgv_uno.jpg