Upholstery and Fabrics - How to repair torn seam in sofa?

I have a sofa where the back of the seat has 2 peices of fabric that meet at the middle. Not sure how exactly to describe it, but the seam is horizontal. The seam has separated and I'd like to repair it, but am not sure how. I am not sure what the fabric is, but it's not a microfibre or anything like that. It is a fairly heavy fabric with lines of piling, almost like a cordouroy, but not quite. I was thinking of using a heavy thread and sewing it, but I don't want to have it tear again from me sewing it. Any info would be very much appreciated. Thank you!

Curious, did you buy this sofa new, with a seam? Usually furniture will not ever have a seam, because it doesn't look nice and because it can't handle the stress of someone sitting on it daily, which is why it pulled apart. The seam was made before it was attached to the sofa and should have at least been reinforced a few times with an upholstery thread. I don't think hand stitching will offer enough strength to hold it together, however, if you use an upholstery thread (#69) and make a ladder stitch, it will probably be your best bet, short of removing all the fabric and having it sewn together on a machine.
I can't think of any other way to repair this other than sewing, and it's impossible to tell if it will hold or not.

I did buy this new. It has the cushions on the back that are not removable and the top of the back is cushy and you can't see the seem because of that. Hard to explain. I just called where I bought it and I'm going to take it in tomorrow for them to look at to see if it can be repaired. Considering this is only 2 years old they better do something. It should not have worn out this fast. Thanks for the info. If they can't do anything, I'll have to sew it.

Hi, I work in the furniture Industry and most manufactures warranty there fabrics for one year (even leather). If you can use a needle and thread, hopefully there is a zipper at the bottom of the cushion. Take the fill out of the cushion and try to repair the seam failure from the inside. Actually not that difficult of a fix but could cost a pretty penny if you have someone do it. Hope this helps.