Right, so you might having the exact same problem that I had, but don't worry I've solved mine so you can solve yours too.You just need to keep few things in your mind and think why is this happening? And please don't do foolish thing like I did which was completely unnecessary and waste of time. I've uninstalled my Arduino IDE because I thought something gone wrong with the IDE, then I "system restored" my computer which was even worse, because I had to reinstall so many software again and I lost too much time in that too. Any way coming to the main point, so what you going do? when you see
Serial port com2 not found or
Serial port com3 not found or
Serial port com4 not found or
Serial port com5 not found
Well, first thing you should do is go on the "Tools" in your Arduino IDE then go down in the drop down menu you will see "Serial Port" if you see it in gray color (like the picture at top) that means something wrong with your USB2.0-Serial driver or driver for your specific Arduino board *you can see my other post for that I've written in detail how to tackle with that problem* but if have already installed that and you are sure nothing wrong with the driver then unplug you arduino borad and plug it again then open your computer's "Device Manager" over here you suppose to "Ports (COM & LTP) like the picture shown below.
Step 2. If you don't find "Ports (COM & LTP) then look at your Arduino bord. If you the light of your Arduino board is dim that means it's time for you to buy another board I mean the board is damaged and that's why it is not working.
Summary: If you see serial port com2 or com3or com4 or com5 not found then that means two things
a) You have a problem with your USB Serial driver or you need a driver for your borad.
b) Your Arduino board is damaged and that's why it will no longer work.
Have you found the solution? Please let me know in the comment below. Thanks