After four years of CIN 1 caused by HPV I finally tested negitive for HPV can it come back again?

Unfortunately... yes. Hpv is often (not always) transmitted sexually. The good news: it can lie dormant and never return. The bad: there are several forms of hpv that can cause anything from genital warts to pre-cancerous lesion to cancer. By using protection with your partner(s), you can help decrease the possible transmission and possibility of having hpv of any type show up again in future pap smears.