Just got a Mega 2560
If I unplug it, then re plug it, I have to restart the computer before the com port becomes available again.
Most inconvenient
When that has happened to me, I just waited about 15 seconds and then plugged it back in.
The Arduino IDE needs a valid com port. If you restart the Arduino IDE, is it working?
If not, there might be a problem with your system or operating system. Which Windows/Linux/Mac version do you use?
Looks like I was being impatient. Sorry for the false alarm!