If you wash netilat yadayim and then a non-Jew says "hello" to you, should you:
- say "hello" back and wash again?
- try to acknowledge him without actually talking?
- or ignore him (doesn't seem right)?
May I call you user1208?
There are 2 questions there:
Even when we have strict standards for interrupting between related brachos, like birchos krias shema, we pasken like Rabbi Yehuda in Brachos 2:1-
ובפרקים שואל מפני הכבוד ומשיב שלום לכל אדם Between the paragraphs, one may greet shalom to someone of honor and he may answer shalom (when greeted) to any man. (loosely)
This is brought by the Shulchan Aruch OC 66:1. The Mishna Berura there brings that one may even greet another who is in between paragraphs knowing that he will answer. This is even more true between netilas yadayim and hamotzi which according to SA OC 166:1 is "good" not to interrupt, but unclear whether there is a violation.
As for whether one needs to rewash because of the interruption- besides the aforementioned non-ruling of the Shulchan Aruch regarding interrupting, the Mishna Berura states there (6) that the entire interruption law, even for those who hold it is absolute, is only lechatechila. After the fact, one need not rewash (unless he became totally involved in another matter).