Why i see some black points running to and fro in my eyes specially in the right one when i look into full white thing?what to do.i'm scared.

Those are normal: Black/melanin pigmentation in your conjunctiva. Nothing to worry!

Vitreous detachment: Floaters are caused by the vitreous (jelly in the eye) detaching from the retina (typically a normal change in the aging eye). The vitreous clumps up or develops blurry areas within the jelly causing your floater. Yes they can be a warning sign. If when the vitreous changes, causing floaters, the retina is torn you are at risk for a retinal detachment. You should have and examination.