Where do I find parts for a computer running windows 98? New install disc?

I am having some major computer problems, the computer was randomly dialing out when offline and popping up spam windows and showing all kinds of inappropriate pictures and ads for all kinds of questionable things, then the computer went silent and smelled hot and a puff of smoke 💨 came out the back.

It appears that the modem burnt looking. There are also burn marks around the thing with metal fins coming out of the big circuit board.

The hard drive is also apparently has burn marks on the circuit board

I assume the hard drive failed and I will have to get a new windows 98 disc and it’s almost impossible to find them. OfficeDepot doesn’t have it. I also can’t find anything like the telephone modem circuit board thing and the modems that I find are totally different and i can’t find a the circuit board that the monitor connects to.

The geek squad service said that the problem didn’t look good and they couldn’t find parts for a system like this, and I could try to track down parts or just junk the system. 

I had a very good system with a 56k modem, 128 mb of ram (later upgraded to 256mb) a 750mhz amd duron processor, a RAGE graphics with 32 megabytes of video ram, Yamaha Sound Card with midi game port, 52x cd ROM drive, and both a 3.5 inch and a 5.25 inch floppy drive. It also had a 20 gig hard drive.

It’s almost impossible to find parts for this rig, should I just junk it? Replacing it would mean learning something entirely new and would it have features my rig has now?