error message when i try to load myrobotlab script

Using Arduino IDE 1.x
1

Hi I have went to the trouble section followed what i thought the problem was tried to update but still get the error

Arduino: 1.6.5 (Windows 7), Board: "Arduino Mega or Mega 2560, ATmega2560 (Mega 2560)"

Sketch uses 10,352 bytes (4%) of program storage space. Maximum is 253,952 bytes.

Global variables use 2,331 bytes (28%) of dynamic memory, leaving 5,861 bytes for local variables. Maximum is 8,192 bytes.

avrdude: ser_open(): can't open device "\.\COM4": Access is denied.

avrdude: ser_drain(): read error: The handle is invalid.

Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.

I cant find a arduino file ( .inf file again. The .inf is in the drivers/ directory of the Arduino software) (not in the FTDI USB Drivers sub-directory of it). can some one tell me where i can get it I have downloaded the ide files again but still cant find a file .inf
thanks for the help

2

Your system cannot open COM port because of it is not working properly or it is locked by another application.
More verbose output during compilation cannot help. It has nothing with compilation but yes it could be a problem with the driver. First of all, check the device manager in Windows if the device is present and if it works. Load the driver in case of missing driver etc. Driver is in the arduino-1.6.5\drivers folder. Arduino.inf should be there for all genuine boards.
BTW: Do you have original or clone board?