If you're referring to the rinkey dink window latches that like to break if you look at them funny then here's what I had done to replace my broken/missing latches.
were manufactured by Creation Incorporated in Three Rivers, MI and AFAIK they have closed up shop. I figured making replacement parts was my best option.
I looked for aluminum stock the same size as the arms (1/8" x 7/16") at the big box stores with no luck so I stopped at a local fabrication shop and had them shear a couple of 3' lengths from a piece of scrap they had in their cutoff bin. After cutting them to length, straightening the twist out of them from the shear and cutting the notches in them the arms were ready.
The pivot part that mounts to the window is a little more difficult to make. I bought some 1/16" x 1/2" aluminum angle @ Home Depot & cut a small piece that then needed some extra bends added to it. The aluminum is brittle so you need to take it easy shaping it. I think I messed up 2 or 3 before getting one that worked.
The pivot was originally riveted to the window frame but I simply epoxied it in place w/JB Weld.
After some careful measurements I drilled 1/8" holes in the arm & pivot bracket then pop riveted them together. They've held up good so far, however I've been very careful when opening or closing them.