Last year we moved out of our old house and into our new house, without having sold the old house. After we took out the very heavy office furniture, we were left with some pretty serious indentations in the carpet. I tried the ice cube method, and that did no good whatsoever. So then I tried the ironing method I found on the Internet. I was amazed!! I sprayed each indent thoroughly with water, then went over and over it with my iron, and re-wet it often until I could no longer see the indentations. In an empty room, they would have been very noticeable, but not so after using my water bottle and iron! Worked like a charm! And the house eventually sold, too.
Good luck!