بسم الله الرحمن الرحيم
Q: If someone breaks wudhu while making tawaaf, does he repeat the tawaaf from the beginning, or complete the tawaaf from where he stopped.
A: I am with those who say the wudhu is not a condition for the validity of the tawaaf. The menstrating woman, the woman with post natal bleeding, and the one in a state of janaba (major ritual impurity due to ejaculation, or sexual intercourse) are the only ones prevented from making tawaaf. Therefore the menstrating woman, and one with post natal bleeding are prevented until they become pure. The one in a state of janabaa is prevented until he takes a bath.
Translated by Najeeb Al Anjelesi
Source: http://miraath.net/questions.php?cat=39&id=4006