I got sick and lost almost all the muscles that I had built. I have recently started playing volleyball. I used to play basketball but the court seems to be a little way from where I live so I can't really go there because of other engagements. I play volleyball for nearly 30 minutes every day at home. I wonder if it will help build my upper and lower bodies.
Volleyball is not strength training. It is a cardio/skill/power sport.
If you are a beginner with respect to strength training, then you will get stronger and see some muscle development from volleyball, but volleyball will not carry you past the very beginner stages of strength training or bodybuilding.
What you gain from strength training will transfer to volleyball: strength and power give you speed, acceleration, and vertical jump height.
What you gain from volleyball will have minimal transfer the other direction.
Volleyball won’t improve your strength. The only thing it may slightly increase is your legs (depending on position). However, If you’re looking to improve your hitting power: work on your chest, back and triceps.