Where can I buy corner sofa fasteners from? The ones that hold the two pieces of an L shape sofa together.?

You can purchase some hardware that works with surprising results...At Lowe's, in the main hardware isle, you'll find some blue specialty hardware drawers. Look for a certain kind of hardware that was meant to hold a headboard frame to a bed frame. They are of steel and will interlock when one is slid down onto the other.I have used these for sofa fasteners will very positive results....It's worth a try..