Baking soda on the burned areas, hot water next.
If it’s Teflon-coated (or similar non stick surface), and it is time to buy a new pan. Those coatings are not healthy when burned and will microscopically flake into one’s food.
If it’s a stainless steel pan, use an SOS type of steel wool on it.
Hi Kathy: What I use is a paste of vinegar and cream of tartar (the dry stuff). Make a paste of vinegar and cream of tartar (use just a bit of vinegar at first as the cream of tartar sort of melts) and put it on the burnt on stuff. Let it sit for about 15 or 20 seconds and then scrape off with a plastic putty knife or one of those plastic scrubbies. You may have to do it a couple of times if the stuff is thick, but usually not. There is no smell and it is environmentally safe. Good luck.
Here's a link with several ideas to try:
Hopefully this post will help you.
Thanks everyone for your suggestions. It was not a Teflon pan and I was able to clean it. I used equal parts vinegar and water and boiled it.