My friend is 2 days late for her period! she took a test tonight and it's negative she's been nauseous and having breast tenderness any recommendation?

Wait and retest: Your friend should retest in 2-4 days, either at home or with a doctor. If nausea and pain are uncontrollable then she should see a doctor before that.

Repeat test later: The negative pregnancy test may show negative for the first two weeks or so. I would repeat the test in another 1-2 weeks. However, keep in mind that a delayed period with those symptoms may well be due to numerous other causes including hormonal irregularities, use of birth control etc.