Like the previous poster said, if you shave, hairs growing back. Not washing enough, or too much and getting soap inside vagina can mess with PH balance and dry things out... Not letting genitils "breath" and air out. Could be getting a yeast infection? If youve had unprotected sex maybe an STI. If youve had protected sex recently and itch maybe a latex sensitivity from the condom... The list goes on unfortunately as to what can cause itchy private parts.
It depends what you mean by itchy private parts. Is it because you shaved and the hairs started growing back or is there hair? Have you had unprotected sex?