YOU SAID:
never gonna let you down never gonna run around or desert you
INTO JAPANESE
あなたをがっかりさせることは決してない
BACK INTO ENGLISH
never let you down
INTO JAPANESE
あなたを決して裏切りません
BACK INTO ENGLISH
i will never let you down
INTO JAPANESE
私はあなたを失望させことはありません
BACK INTO ENGLISH
i will never let you down
That didn't even make that much sense in English.