Haha, I'll try to answer that literally - if you ever find yourself this happy or sad you'll probably need to get some help.
The MOST over-the-top blissful and melancholic I can think of:

: Mozart's Jupiter Symphony, especially the last movement.

: Stockhausen: Adieu wind quintet - wrote it in memory of the son of a friend of his that was killed in a car crash. One of the rare instances this composer tries to evoke emotion in his work, but, of course still hard to listen to; grossly depressing, and very effectively reflects sickening and debilitating bereavement a little too well.
Definitely not something I want to listen to to jazz me up b/f I go to work in the morning.
Also, Chopin's c minor Nocturne mentioned above is definitely on the list.