I got my nose pierced 4 weeks ago but its still scabs a lot and sometimes the piercing keeps popping out. what shall i do?

Have you been looking after it properly? And are you sure it's a scab? All piercings will leak lymph while healing; it will dry around the area and look like yellowish crusty stuff, kind of like the crusties in your eyes when you wake up each morning. This is normal and is a sign that your tissues are healing.

If it's bloody, then there's a problem. My cartilage piercings would bleed a small amount from time to time during healing if I irritated it or bumped them roughly against something (yeah, tragus piercing + glasses = ow). If the jewelry keeps popping out maybe you should have a different kind of ring put in by a reputable piercer. This was the case when I got my third cartilage piercing; I went with a barbell but the bead kept coming off no matter how tightly my piercer screwed it back on, this happened so frequently that I had to drop that idea and I got a captive bead ring put in instead. The little sucker hasn't fallen out once!