I'm just learning the terminology here, so bear with me. Wife's earring went down the bathroom sink. When I removed the P-trap, the connecting PVC segment going into the wall ("sanitary-T"?) was very loose - not a tight connection to the pipe behind the wall. Looks like somebody gave up trying to do it correctly. I want to make it right but can't figure it out since I have little plumbing experience. The attached picture was taken while lying on my back looking up at the connection. It looks like there is a metal "slip-nut" (female) screwed onto some sort of connector that has two exterior-threaded ends (both male), one end attached to the slip net and the other going into the "sanitary-T". It looks like the nut is actually screwed into another fitting before going to the main vertical pipe. I thought the proper thing to do would be to remove the slip-nut and screw on a metal Melvin connector, as I saw in a video, with one female end and one male end. And then attach a plastic pipe to the male end with another slip nut, and that segment of pipe would go to a new P-trap (?). BUT I CAN'T GET THAT METAL SLIP-NUT OFF! - if that's what it is (?). I'm not even sure. It's hard to tell. Anyway, I've already removed a bunch of drywall in order to get a decent grip with a pipe wrench. Tried a small wrench and a monster wrench, and couldn't get the nut to budge, but I don't have much room to work with. Considering something more drastic like removing the cabinet and sink and cutting away even more dry wall so I can really get the large wrench in there, but I'm afraid the nut still won't budge and may actually get damaged so it will never come off. Also thought of just sliding another PVC or metal pipe into the the joint, as is, with just some sort of adhesive to hold it, but it wouldn't be a smooth, tight fit. The inner surface of the metal is not exactly flat cuz it's not one piece and is actually 2 fittings (I think), so I don't think it would be a solid connection even with the adhesive. Any advice or clarification on what I'm actually looking at? Really can't afford a plumber right now.