uploading standard firmata example

I am unable to decode the error shown while uploading standard firmata example on my arduino uno board.

this is the error shown to me:

Arduino: 1.6.5 (Windows 8.1), Board: "Arduino/Genuino Uno"

Sketch uses 12,194 bytes (37%) of program storage space. Maximum is 32,256 bytes.

Global variables use 940 bytes (45%) of dynamic memory, leaving 1,108 bytes for local variables. Maximum is 2,048 bytes.

avrdude: ser_open(): can't open device "\.\COM5": The system cannot find the file specified.

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.

Can you upload ANY sketch to your Arduino?

I checked uploading some other programs after your reply and it's not uploading. It's showing the same error. Can you help me out with the error.....

Can you help me out with the error.....

It's fairly obvious, isn't it. Some application has the COM port that the Arduino is connected to open (or failed to close the connection properly). Since it is Windoze, you probably need to reboot.