Taking a 4 day break from combined oral contraceptive, been 3 days of the break & still no withdrawal bleed. if i resume the pill on day 5 before i bleed will it prevent the withdrawal? or stop it if it does start? will i be protected from pregnancy?

Depending on when in your cycle you stopped, and how long you have been taking them, ovulation may or may not have taken place and therefore bleeding may be delayed. Without the pill your body tries to recalibrate to original hormone levels which may take some time. You are not protected if you stopped oral contraceptive during active pill days.