Yeah, it the one that goes "da da daaaaaaa dadaaa fafaaaa dadaaa da..."

Are you into musicals perchance? To me this sounds almost exactly like the chorus of "I Still Believe" from "Miss Saigon". Is that it?

P.s: you have a super nice voice!

P.p.s: made an account just to comment this because I have the same issue sometimes and I'd hate not knowing!

P.p.p.s: for anyone who hasn't seen it, can highly recommend (though some racism/stereotypes to be expected), the storyline and music (and The Great Lea Salonga) are absolutely 🔥

P.p.p.p.s: the first 14 seconds could also be "Auld Lang Syne", but that's not what you were going for probably

Have you tried Midomi? Supposedly it can find songs just with humming or singing.

You can trys Shazam or Google and just hum it Most oft the time they can identify the song

It's the Cloud Atlas Suite by Vyvyan Ayrs.

Some audio maybe? I don't think many people here can read music sheets properly to make sense of it and help you finding the tune. Audio file will help tremendously.

It sounds like the kind of melody that would go over top of something from Two Steps from Hell.

Unfortunately it's not one I know and I'm not too familiar with their recent releases. But maybe it's something from them or a similar "epic music" producer that you heard recently, once or twice, and it got lodged in your subconscious.