how many brothers and sisters had holy prophet

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

As far as we know, the Prophet did not have brothers and sisters from the same father and mother, but he had foster brothers and sisters among whom are:

Abu Salamah ‘Abdullaah ibn ‘Abd Al-Asad and Hamza ibn ‘Abd Al-Muttalib and they were suckled by Thuwaybah, a female-slave owned by Abu Lahab.

Among whom also are ‘Abdullaah ibn Al-Haarith and Unaysah bint Al-Haarith, and Juthaamah bint Al-Haarith (Ash-Shaymaa’), and Abu Sufyaan ibn Al-Haarith ibn ‘Abd Al-Muttalib, and they were suckled by Haleemah As-Sa’diyyah.  

Allaah Knows best.