Training through injuries is a challenge but depending upon the severity of the injury and the way you attack that injury can make all the difference in the world in how fast you recover and better, how fast your game can recover.
Muscle strains and joint sprains are the worst because usually they heal okay but can come back as you will be using these joints and muscles to play racquetball.
Add that to the fact that most of us think we are a little better than the general population at healing. We tend to rush into action too soon.
One year a friend of mine and I sprained our ankle the same day. He ignored it and rested. I used ice every day and wrapped my ankle and tried to keep it elevated as much as possible. I was playing in one week. He took three weeks before he played again. How you treat the injury is huge.
If it is an arm, your racquet arm, use the rest of your body to train. If it is a leg, walk if possible, and in other words, do what your body will let you do so you do not lose conditioning.
What about your mind? You have not sprained your brain have you? Use visualization. What were you working on in practice before you were injured? Dial that vision up in your mind and get practicing!
One more thing I should add to this. If a Doctor says to do something, follow the directions. The morning after my first hip replacement the doctor told me to stay in bed until Physical therapy. I got up and did a few laps around the hospital halls. When I got back to my room my leg looked like the Hindenburg blimp; all blown up! I was trying to heal up fast and instead I set myself back.
Take care of the injury and use your mind! You will be back on the court in no time!