I was constipated for 4 days so i took laxette just 1 square at night next morning i developed diarrhoea i had already taken yaz (drospirenone and ethinyl estradiol) will it effect it?

No effect: Diarrhea does not affect birth control pills effectiveness.

No: When you take a birth control pill - this gets essentially absorbed in your stomach and small intestine and hence when you separate out the laxative and birth control pill by more than 2 hours - the laxative will have no effect on the pill whatsoever - so you remain protected.