In the trilogy of the movies, at the very beginning Galadriel says a few words starting with "The World is changed. I feel it..." In the background the words start in Elvish "Yamma presta..." What are those words?
Here's a site that talks about linguistics in the Lord of the Rings movies. According to it, the complete line is:
I amar prestar aen, han mathon ne nen, han mathon ne chae a han noston ned 'wilith.
which -- as you'd expect -- is a Sindarin version of Galadriel's English lines:
'The world is changed; I can feel it in the water, I can feel it in the earth, I can smell it in the air.'
Note that the movie gives these lines to Galadriel, but in the book, they're said by Fangorn to Galadriel, in a very different context: it's in chapter 6 of book VI, and
he's lamenting the fact that, because the world is changing, the two of them will likely never meet again.
One further note: the attempted transcription in the OP is missing the Rs at the end of "amar" and "prestar." This can probably be traced to Cate Blanchett's non-rhotic Australian accent creeping into her Sindarin pronunciation; in Tolkien's elvish languages as correctly pronounced, that R should always be audibly rolled. The pronunciation chapter at the beginning of Helge Fauskanger's Quenya course has some remarks on this kind of thing (mostly about the correct pronunciation of "Mordor").