Soaked a shirt in stain remover to remove makeup and the buttons on the shirt have rusted onto it. how do I get the rust stains out?

Well, you're going to have to replace those buttons. Go to a sewing shop and try to find buttons that are the same size. Walmart has a sewing section. You might be able to find replacement buttons there. As for the rust on your shirt, first remove the rusty buttons....all of them. Then soak the shirt in white vinegar, straight from the bottle. Do not dilute the vinegar. Soak the shirt for about 45 minutes. Then launder using the hottest water temperature recommended on the care tag. This should remove the rust. If the rust is very stubborn and the vinegar does not remove it, you can remove the rust with a product call Barkeeper's Friend. Barkeeper's Friend is available at Home Depot. Make sure you buy the LIQUID Barkeeper's Friend. Just rub the Barkeeper's Friend into the rust stains. Let that sit for about a half an hour. Then launder as usual. If you do not have a Home Depot near your home, you can buy Liquid Barkeeper's Friend on Amazon, but it does cost a little more on Amazon. Here is a shopping link for you: http://www.amazon.com/Bar-Keepers-Friend-Liquid-Cleaner/dp/B007UTJR7G/ref=sr_1_3?ie=UTF8&qid=1398098460&sr=8-3&keywords=barkeeper%27s+friend Whatever you do, do NOT bleach the shirt. Bleach will make the rust stains permanent. After you have removed the rust, sew on the new buttons. Don't sew the buttons on tightly against the fabric. Allow just a little slack so that it is easy to button the shirt. You want to use several passes of thread but you don't want the buttons to be too snug against the shirt. Good luck.