nos·tal·gia

nos·tal·gia /nɒˈstældʒə, -dʒiə, nə-/
–noun
1. a wistful desire to return in thought or in fact to a former time in one's life, to one's home or homeland, or to one's family and friends; a sentimental yearning for the happiness of a former place or time
2. A bittersweet longing for things, persons, or situations of the past