I wanted to upload a sketch to my Arduino Nano so I connected it to PC via a mini usb cable. The sketch compiled correctly but it got an error regarding the COM ports. I then too a look at the ports option in the TOOLS section and it was grayed out. I tried to update the driver in device manager but it can't detect any port or additional usb port.....
Can anyone please help me with this problem...? 
Try using a different known-good USB cable or test the cable you're using on a different device to verify it works for data. You may have a charging-only or defective cable.
If you're using a USB 3.0 port on your computer use a USB 2.0 port instead.
If it's a clone, it probably has a different USB-serial adapter - either CH340G or CP2102 instead of FT232. These require different drivers. The serial adapter is the second largest black chip on the board (the largest one is the microcontroller) - check the markings on that; if it's not FT232, google for the part number, your OS, and the word "drivers" - the drivers are readily available.
I had the same problem, soon after that the PC went down and Windows had to be reinstalled (I later tried this on a Mac with similar, yet less severe results), so be careful