payphones. There have been times when I really needed one (cellphone was broken), and was really frustrated that I couldn’t use a payphone. It was particularly frustrating because the payphones themselves still exist, but no one sells phonecards anymore, so they are not useable.
My friend’s husband actually tried buying a typewriter because he wanted to be able to type up his Divrei Torah and didn’t want a computer in the house. He couldn’t find one. So he had to buy a computer in the end, but he calls it a word processor instead.
I tried buying a CD player recently and the guy in the store seemed not to know what I was talking about. All my friends seem to have CD players, but I guess they bought them 20 years ago.