How To Terminate Pregnancy?

i had a friend who asked me what to do aboput her pregnancy.. she got an abortion last dec. and got mentration last jan. 26 this year. she is worried because her menstration did not occur.. she dont wat to get preganant. what medicine will you advice to take in order not to get preganant? she said that she had urine test and it is positive.. her boyfriend doest know about it.