Replacing a Button
If a button comes apart off your upholstered furniture, I would suggest that you have another button made at an upholstery shop or at a do-it-yourself fabric shop. You will need some of the fabric, which you can sometimes get from an armcover, or from somewhere under the sofa. (you may have to take some of the dust cover loose to find a piece of fabric big enough to cut off. Another possibility is to carefully take the old button apart and use the old material from that button to make the new button. An upholstery shop would probably be more able to help you with that. The new button will probably have a loop on the back side, so you will also need to get a button needle and some button twine.