Controlling buzzer

Do you guys know how to turn on buzzer every 14 days

Yes

What hardware do you have and what have you tried ?

Im using arduino uno,i never tried it, but i've done some research and im completely lost right now

Start by looking at the BlinkWithoutDelay example

It turns an LED on and off every second. If you set interval to a longer value then guess what happens ? Need to have a long off interval followed by a short on interval ? If so, change the value of interval when you change the state of the output