Quote by myearshurt
When you change the key of a song, what happens to it? Does it's overall sound change completely? was just looking at Minuet in G and D minor

It changes key... If a song changes key, it could just mean the exact same thing, but up a step, or they could change the piece completely.
If it goes from a minor to major, then it'll go from happy to sad (most likely). I don't know if the use of ternary form constitutes as a key change, but in that structure it goes from the Minor key, to relative Major, and back to minor. Or the other way around. It's all in the way that it's changed, you might not even hear it without trying to play it and see where it resolves or looking at the score of the song.
One common example of a key change is to move the key, and all other parts of the music, one tone upwards, eg. G major to A major.

This is used a lot in pop music, especially in songs which are very emotional but have a major chorus. Changing key like this usually gives the song a sort of uplifting effect which makes tends to make people feel more moved. It's usually used near the end, like in the last chorus.

I can't think of any song that has this off the top of my head, mainly because i try to avoid most of the sorts of music that have this sort of stuff in, but listen around and you'll probably find it. Maybe some Leona Lewis...