Removing Carpet Depressions Left By Furniture Legs

Moisten the area with hot water. Cover it with a damp, white, disposable towel. Press
a hot, steaming iron to the towel for up to 90 seconds, being sure to check the carpet underneath for signs of damage such as scorching.

This will soften the backing of the carpet and after removing the iron you can work the backing up so that it is flush with the rest of the carpet. This will not work on all carpet types.