loud pop, came to a stop, currently doesn't shift into gears doesn't go 2 P,

What is your question?

A week ago I was at a complete stop fave the jeep some gas I heard a loud pop, managed to "roll "off the rd. Now it starts but won't go into any gear and won't go into park, I can push it and it moves, a good friend who knows more than the average joe abt cars, took a look and changed my trans fluid it was low and really dark. Still no luck, he got under the jeep while I shifted into gears, said it wasn't moving into gears. Now thinking it could b several things told me to get diagnosed at a shop, 5 days later they call and say it's the transmission, I asked how they knew he said we tested it( umm yeah) and the fluid was good, I reiterated I just had the fluid changed that's why it's good, said he'd check again thinking it'll b another 5 days, help! Any opinions thoughts? I has two ppl say they didn't think it was the transmission bc it wouldn't go into park, thoughts on that pls? We're moving soon I gotta either fix it or get a new car, and I don't want to b scammed