I had received a depo shot 9 days ago , and had unprotected sex on the 9th day . so i took a plan b . will the plan b effect the depo shot ?

Protection from what: It turns out that regular Depo-Provera shots every 3mo is very effective at preventing pregnancy. It's not 100% effective but as close as we can get if you get shot in timely manner. So Plan B emergency contraception isn't necessary nor will it affect Depo-Provera. But no hormonal birth control protects against sexually transmitted diseases/infections. That's why condom use is still necessary, too

Neither medication: will interfere with the other- but Plan B is not necessary if you just had depo provera administered.