Heavy furniture items often create problems by leaving marks of compression on the carpet, which become visible when the furniture item is moved to another place. The best way to avoid these marks is the use of felt protectors under heavy pieces of furniture especially chairs. These are easily available in the market or you can make some at home.
You can remove these compression or indentations in the carpet by using blow dryer on the high heat setting and use a fork to gently move the carpet fibers in a upward fashion until the indentation marks are gone.
You can remove these indentations in the carpet by pouring a little hot water on the area and letting it dry. Hot water after drying will tighten the carpet back to its original shape. This method is also good to remove wrinkles in the carpet just add more hot water. Try it first on a small out of the way area.