How to tell ur parents u lost ur kEys?

I dont know how or when i lost i just know i did. I guess this is my third or fourth time so im sure theyll be mad!! But school is starting and i need to do this now. I have to and i want to.... I dont to lie with them. My relationship with them is getting better and i dont want to ruin that. So please GOD and someone else help me cuz i DONT KNOW WHAT TO DO!!!