Violation for a drug trest failure is evidence he is not obeying the terms and conditions of probation. However there may be reasons to reinstate. Consult a local attorney to help this person out. Good luck.
Every case is differnent as is every jurisdiction and sometimes judges within the same jurisdiction see things differently. It appears your friend was sentenced as an adult. If he's been doing well on probation and if he's amenable to drug counseling he might get reinstated, but no one can know that is not directly involved with his case and familar with the Judges philosophyin cases of this type.
A lot depends on what has happened in the past two years, the prosecutor, and the assigned judge. The judges in Hillsborough county can be fair, but they will view a positive drug test as a way to teach you a lesson. That could mean more restrictions, or even jail, depending on your age. I practice in Hillsborough county if you wish to give me a call.