Maybe you have some other violations that are not related to Crypto advertisements because the banning of Crypto advertisements related advertising will take effect on June in which applied to the ICO only not to the personal accounts. If the twitter say its multiple or repeat violations then you have given a warning for multiple times already before finally banning you. Try to recall if there are violations that maybe you have done like successive following other accounts in just one day just to gain more followers in return, try to remember it to make your mind at ease.