I found an old abandoned 1999 diamondback outlook that im trying to repair. The crank is bent as well as the front chainring. I bought a universal crank remover from Parktool. I unscrewed and removed the crank bolts. Then i screwed in the crank remover. It worked great for the non-drive side. However, when I tried to use it on the drive side I wasn't successful at all! I couldn't even screw the crank remover into the crank arm because it's so badly stripped and even has a couple of chips in it. How can I re-thread or remove the crank and chainset to replace them?
Option 1 - try and back out the drive side cup while working around the crank. Since you've removed the NDS crank and cup, the whole mess should be able to come out the drive side and into the recycle. Note the drive side cup is left-hand thread.
Option 2 - Use a hacksaw or a grinder with a cutoff wheel, to cut the axle between the frame and right crankarm. Avoid damaging the frame, but the cup should provide enough protection. When it comes off, salvage anything you can then to the recycle bin. Then you can access the drive side cup easier.
You're going to need a new bottom bracket assembly, which probably means a cartridge. You also need replacement crank arms to match, and possibly chainrings if the old ones can't be straightened. The old pedals may still be serviceable though.
Sounds like a fun project ! Feel free to include photos with your question, or progress photos in an answer of your own.
Unior (and I think a couple others) makes a tapered crank remover for trashed crank threads.