Can i ovulate on the 20th day into my cycle if i took plan b on the 10th day?

Possible: Plan B is a high dose of hormones designed to disrupt or delay ovulation. After taking at your menstrual cycle will be "off" so late ovulation is possible

Yes: Plan B can cause late ovulation, so it's hard to predict when you might ovulate.

Doubtful: Plan B is a progesterone and would not be likely to impede ovulation. The estrogen level is the functional component in the drive to ovulation. When the estrogen level reaches an adequate level, the LH surge is triggered which results in ovulation. The transient increase in progesterone would not affect that relationship. There could be other factors that might delay ovulation.