Problem with upload files to ''Arduino Pro mini''

when i going to upload files to arduino pro mini following error massage apper,

Arduino: 1.6.8 (Windows 8.1), Board: "Arduino Pro or Pro Mini, ATmega328 (5V, 16 MHz)"

Sketch uses 1,066 bytes (3%) of program storage space. Maximum is 30,720 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2,039 bytes for local variables. Maximum is 2,048 bytes.
avrdude: ser_open(): can't open device "\.\COM12": 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"
option enabled in File -> Preferences.

please help me to overcome this problem.thank you.

It seems to be saying that COM12: doesn't exist. Does it show up under Tools->Port?