Obtain a replacement doorknob. Besides the style, look for something solid that will hold up to regular use and last a long time. Also, consider whether this will go on a bedroom, bathroom or closet. Should it have a privacy lock? If you have lever-style handles and a locking handle, you will need to get a right- or left-handed handle appropriate to the door direction. Buy a doorknob with a pawl the same length as the one you are replacing