What is the meaning of nastagic?

It seems there might be a typo in your question; perhaps you meant "nostalgic." Nostalgic refers to a sentimental longing or wistful affection for the past, often associated with memories of happier times or experiences. It can evoke feelings of warmth and comfort, but also a sense of loss for what has gone by. The term captures both a yearning for past moments and the bittersweet nature of reminiscing.