Replacement

I don't know if this is a tilt latch or another name, but I have several windows that have these broken pieces. The windows were from a company called Napco and about 20 years old. The plastic piece has broken off inside therefore I am no longer able to open these windows since that piece is what holds them in the track I assume. I am about to sell the house and the buyers are insisting on having them fixed. HELP. I found your site and it looks like something might work, but I can't even begin to know which ones to buy and how to fix them. I hope the pictures are good enough to show these little latches. Thank you, Barb