My penis has a cut that hasnt healed for 3 days. havent been sexually active in 5 years. could this be herpes? i never had a case of herpes before but can it manifest years later? i also happen to have penile lichen planus?

I believe it is unlikely to be genital herpes in your case. People with lichen sclerosus, which is an extremely itchy condition of the penis foreskin or glans or vagina, do develop cut like areas in the involved skin. I'm not sure if this also applies to lichen planus involvement of the penis glans. A dermatologist is best to evaluate and advise you.