Move any furniture from where the marks are and place the items in another room or area.
Start at one end of the furniture mark and use the edge of an old spoon to work the fibers of the carpet back upright. Use your fingertips to blend the fibers together.
Fill a bucket or pot with three cups of cold water. Pour about a 1/2 tbsp. of water into the area where the furniture mark was to dampen the fibers. Do not totally saturate the carpet --- you only want the fibers damp.
Heat the carpet fibers with a hair dryer as you work the fibers upright with the old spoon and your fingertips. Continue heating and working the carpet fibers until the fibers remain upright and the indentation is gone.