If you think some will do black magic on you or you think someone has done it. for all cases of black magic and for future protection too. Please do the following always. No one will ever be able to harm you through black magic. No black magic will work on you. For protection of whole family please after reading it do a dam (blow) on a glass of water and give it to everybody everyday to drink. 

After fajr and Maghrib Salah  

Draood/Salavat once

Ya Qabid0 (Allahs Name) 21 times

Darood/ Salavat once