You have had sex with someone who is not infected with hiv. but after a few days, a lymph gland appeared in the neck, which is not visible, but it can be touched, and now it continues for about 8 months i am worried what to do?

This doesn't sound abnormal -- most likely just a normal lymph node or other tissue irregularity. "What to do?" Nothing seems necessary, but if you remain concerned, see a doctor for what will probably be a reassuring evaluation. For sure do not keep trying to feel it: repeated self exam can inflame or enlarge such things, creating even more concern and confusing medical evaluation.