Soak

As others said, soak and simmer them. I do a large batch for the week and you can use them as canned beans would, but it tastes WAY better. Keep the broth too, it’s good stuff.

I would second what another redditor said about taking your laundry to somewhere that does it for you but if not: gather all the dishes in the room, put them in the sink and fill with hot soapy water to let soak whilst you load the washing machine. Then start washing. While laundry is being done you can reassess what's left in your room aka what belongs there and what doesn't.

I believe soaking into a solution of warm water and oxiclean for about 3- 4 hours and then regular cycle in your washing machine should do the job.repeat if needed. Also try scrubbing the spots with a toothbrush and dish soap for the most resistant ones.

Made a post myself asking about this in /r/adulting a few hours ago. The general consensus i got was to soak in hot soapy water for an hour and then scrub them. They probably won't ever look brand new again but they'll look better. I was also advised that oven cleaner would work great too.