How can I fix my warning buzzer on my Nissan Frontier 2004?

Hi I purchased a 2004 Nissan Frontier and I thought I once had warning buzzer working on it and now I don't? How can I fix that issue? It does not buzz when lights are left on? When door is ajar? When Seat Belt is not on? and when keys left in. Thank you for your time and assistance to this very annoying matter.