You will need to find an area where you can reach up safely. Standing with your feet parallel to your shoulders, cross your arms over and gradually lift your arms above your head, reach up as far as you can making sure you do not over stretch.
Don't ever under estimate the importance of stretching and the benefits it holds.
The Reach-up Back Stretch can help with neck muscle strain, whiplash, cervical nerve stretch syndrome, wryneck, upper back muscle strain and upper back ligament sprain.
Always remember that while stretching may be recommended to aid recovery out of injury, you should always be very careful when stretching through rehabilitation. Your soft tissues are likely to be more vulnerable to re-injury if you stretch too much or too hard during this time. Always check with your Health Care Professional who is guiding you through your recovery to make sure it is appropriate to start stretching, and please - ALWAYS FOLLOW THE RULES FOR SAFE STRETCHING (The first posting on this stretching blog).
Image taken from "Upper Body Stretches" wall chart by B. Walker.