Cannot find COM port for Arduino after replacing Atmega328p
Generally the IDE will detect one it can use, so you shouldn't need to use the Device Manager.

When you select the board type, so far, so good.

Then when you ask it to pick the port, it will present a list of ports that it has discovered that are registered in the Device Manager.

One thing you will notice is that if you have a Genuine Uno, for instance, it will list that next to the port name.

But if you are using a board (of any type) that have the CH340-type port it will show just the COM9 or whatever it finds.

If it doesn't find any ports (My laptop always detects the COM1 port on the back that I never use so in my case if that is all it finds then it is not finding any USB ports)  then jump ahead to the arrow below.

So by trying each one you will find a port that works with your board.  Or not.

I am sure you have already seen the errors it throws when you use a port that won't work for you.

----->  If you have tried all the ports listed and none works, then you are left with only a couple of possibilities:  Either the cable is bad, or the board is not responding.  

Ultimately, it doesn't matter what it says in Device Manager if the IDE won't use it.

So if you can find another board and see if the cable works that would eliminate the cable as being a problem.  

But if it simply will not respond then look above in the comments at what @Majenko said.

Good luck.