I run, but never walk. I sing, but never talk. I awaken, but never shut down. What am I?

That's a tricky one, but the answer is: A clock. A clock runs, but doesn't walk. A cuckoo clock can sing. An alarm clock can awaken you, but not shut you down. A similar riddle goes "What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?" The answer to that one is: A river.