I am using IDE 1.0.6 and I want to change the serial port but I can't click the button for serial port please help.
Which operating system?
Which board? Original or clone?
Did it work before?
Have you tried another usb cable?
windows 10
board: arduino uno r3 original
yes it used to work on IDE 1.8.2 but due to bugs I switched to 1.0.6
I do not have another usb cable to use with this only the blue one I got
Any yellow triangles in device manager when you connect the board? Sounds like you need to install the driver.
no I don't see any
So is the board recognised in device manager?
no,I don't see any thing related to arduino in it
Clearly windows does not recognise it. Any typical sounds when you connect the board (I doubt it but must ask)?
Bad usb contacts at either the Arduino or the PC, bad cable? Anything connected to pins 0 and 1? Faulty board is the last option.
And after that I'm probably out of options.
no sounds when I connect to board,nothing(at least to me) seems wrong with the cable nothing connected to pins 0 and 1
ujwaljoshi:
yes it used to work on IDE 1.8.2 but due to bugs I switched to 1.0.6
Which bugs?
like where it says error compiling for board over and over again,I asked about this here and someone advised me to use a older version
(talking about this thread)
Did you try 'normal' version of 1.8.2 instead of Windows Store version?
I'll try it now
still not working I try to change com port for it but it dosen't give me an option to do that
Is it possible your USB port has failed?
Use an USB mouse to test.
Just an idea. 
Could be a faulty ATmega16U2. You could try putting it in DFU mode, and check if it's detected. Maybe try DFU'ing it.
Does the LED on pin 13 blink when you reset the board? If not, the ATmega328P is probably dead as well.
Do you have another computer to try it on?
Pieter