I have been taking vitamin d and vitamin c for a year. did both of them absorb or accumulate in body? if they are accumulated is it bad? what do i do?

Can be, thus check: blood concentrations of vitamin D3 (D3, not just D or D2). The fat soluble vitamins are the ones more easily overdosed & dangerous. Yet problems are commonly way down the road; subtle or sudden. Overdose with water soluble vitamins, e.g. B group & C, is more difficult, yet research on taking C >500 mg/day correlates with ↑ed cardiovascular problems. No easy way to recognize on individual basis.