The past form of need to is needed to, while need as an auxiliaryA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") is used with perfectThe aspect expressing completion. E.g.: He’s finished university. infinitives only in negativeA declarative sentence indicating "no". E.g.: Tim has no friends. sentences to refer to past timeA concept which is related to our perception of reality; that part of existence which is measured in seconds, minutes, hours, days, weeks, etc.. Note the difference between didn't need to and needn't +perfect infinitive:

"Do you need to use the hairdryer?" "Yes, I do."