If it were not wool, I would say wash it and see if it bounces back. How does the yarn skein label say to clean it? Once I steamed a baby sweater on rather high heat, and I accidentally pulled a front half and stretched it. I could never get that half back to its original size--I had heat set it.

I ruined an acrylic shawl by doing exactly what you did. Nothing I tried to do to fix it worked. Washing it did not help. The shawl remained very flat and shiny. Acrylic fibers are ruined by steam pressing and heat. You can email any of the manufacturers to confirm this. However, this is what I did: I cut off the ruined part and crocheted it over, since it was just the outer half of the shawl. Lesson learned, and I vow never to do that again.

quirkpod, ME TOO!