Any idea how it got creased? If it was tossed in a closet and got folded up it may be fine after being laid out for a while. If it got wet or has been like this this since new could be a problem. Check the back to see if it has become de-laminated.
Is it Clean ? Sometime just a good washing with proper and controlled drying can flatten a rug. Steaming a dirty rug can open up Pandora's Box. Before you clean you do need to know how it is constructed. Lowes and Pier One sell all kinds of rugs manufactured in a lot of different ways.
Washing on most rugs takes care of this. If it is a latex backed rug, or synthetic foundation, it could be creased from being folded, stacked on, etc. - and it's hard to get these out. Hanging them on racks to dry is notorious for creating creases if you are not careful.
Sometimes i roll the rugs from the length side rather than the normal width way. Tight roll, tie it up, and let it "learn" a new shape. Sometimes I roll them inside out. It depends. A photo would REALLY be awesome on this. We are pulling answers out of the air here...
I'm with Lisa on this one, without pics it is very difficult to give good advise. I propose that if you want serious help on this forum then you gotta be serious enough to take some pics and post them.
I just said the same thing on the "yellow on a wool rug" post... the real serious rug cleaners know there are so many different avenues on this, all wool does not react the same, and there is not just one type of "yellow."
With phones and digital cameras - it's just too easy to get photos, so no excuse! You risk buying a rug if you do something dumb... so protect yourself by giving all you can so you can get a real response that helps.
I wish I could help more on this thread... I just have no idea what kind of rug we are talking about!