Did Ptolemy have a brother?

Because this question was in the Cleopatra section, I am assuming that you are asking about Ptolemy XIV, her brother. Yes, he had at least one brother, who was also called Ptolemy and reigned as Ptolemy XIII.
If you are not asking about Ptolemy XIV, then you are asking about an unidentified one of the other Ptolemies, of whom there were many, including fifteen Egyptian kings, the famous astronomer Claudius Ptolemy, and ten or more others. In this case, the question is unanswerable.