How long can tendonitis and a muscle tear take to heal to play sports again?

1. Depends on the tendon/muscle area and the specific sport. With complete rest and focused treatment, most of these issues can improve within 2-4 weeks. More complex areas and pathology can take longer.
Varies. There is no good answer for this. It depends on where the tear is, how severe it is (partial or complete) as well as the persons own healing ability. Every rehab program is individualized but i would say that in best case scenario, people can get back to sports after 4 weeks of rehab and in worst case it may take 6 months or more. Sorry for being vague but there is no good answer for this.