What can I do about indentations in my carpet?

Indentations from furniture re-arrangement are a normal phenomenon in carpet. Sometimes, the situation is self-correcting when the furniture is moved and the carpet backings and pile are allowed to re-acclimate. In other cases, vacuuming coupled with light brushing can bring up the indented areas. In extreme cases, the indentation can be covered with a damp towel and steamed with an iron for a few seconds, followed by brushing while warm to "resurrect" the pile in that area. Nylon carpet pile (about 70% of residential carpet) responds particularly well to this procedure.

There are, however, limitations brought on by the type of pile fiber. If the pile is made of non-resilient olefin, as in olefin Berber or level-loop olefin commercial carpet, the indentation may be permanent. That's a characteristic of the fiber. This is why non-resilient olefin often is combined with resilient nylon in several popular carpet styles.

FROM IICRC.ORG