I was told to take all my antibiotics for my sinus infection, I missed a few weeks. Do I get back on them.?

Do not recommend. I am not sure if you mean you missed a few doses and it has been a few weeks and you are now feeling poorly again, or if you were supposed to be on the antibiotics for weeks. Either way, if you missed doses and you are not feeling well again, i would recommend you go back to your doctor because the bacteria are more likely to be resistant to the antibiotic you were on, and less likely to work.
Missed Antibiotics. If you stopped taking the antibiotics more than a week ago, don't resume. Antibiotics should always be taken for the full course prescribed. Whatever bacteria remain alive after a "partially" treated infection are more likely to be different than what were present when you started the antibiotics. Go back to your doctor to get a more broad spectrum antibiotic, and complete the full course.