Dead hangs are one of the best things you can do to repair and strengthen almost all of the muscles of your shoulder. It lengthens the muscle and helps realign them. If you can, hang from a ledge or pull-up bar as long as you can and repeat a couple times a day.
If you cannot support your full body weight or it causes too much pain, you can place one foot on the floor or a stool for support.
The top shelf of a package car works great for this.