Can't find serial port

Hi, I’m new to arduino, and I just got my lilypad with FTDI breakout board connect to my computer’s USB, however it can’t find the serial port, I tried to reinstall, restart the computer, and still not working
Any suggestion?

What version of the Arduino IDE are you running? On what operating system?

Links to the hardware you have?

however it can't find the serial port

"it"? What can't find the serial port?