I have experienced the same problem...but was luckily able to fix it with advice from all of you!
My Story:
My MacBook is extremely new...I have had it for a little over a month. I just graduated high school, and since a MacBook was a requirement for my department at college, my grandparents bought it for me as my graduation present (which was extremely nice of them)! You can imagine how nerve-wracked and anxious I was when I plugged in my iPod (using a cheap, third-party cable) and the thing completely shuts down. When I tried turning it back on and it did not, I can not even begin to describe how upset I was, knowing that I might have just killed my computer, lost all my data (that was saved from a previous computer), and on top of that, would have to buy a completely new one, telling my grandparents that I just threw their $1000 down the toilet.
Upon finding this thread from my iPod, I couldn't believe my luck. I saw all the advice on the first page (but for whatever reason, did not check the following pages) and just let my computer sit. I saw someone recommend letting it sit for around 30 hours. I left it sit for 40, just in case, and when I attempted to turn it on: no go. As my worry increased and the pit in my stomach I had been carrying around for 2-3 days dropped a little further, I once again found my way to this thread. It was then that I noticed the second and third pages to this forum. I saw many people advising to take the battery out, which I was scared to do because I did not want to void my warranty with Apple.
The Fix:
Then I stumbled onto the posts that recommended I simply disconnect the battery from the motherboard, ensuring that it would not void my warranty. I only unplugged it for about 30 seconds, convincing myself that if it didn't turn on, then it would be because I had not left it unplugged for a long enough period of time, and I could have another try at it; basically preparing myself for another failed tip. BUT LO AND BEHOLD, IT WORKED! My computer booted up, no data was lost, and I was even able to reopen the tabs I had up on Google Chrome at the time the computer shut down. I am typing this post (on my newly fixed MacBook 🙂) in the hopes that someone will read it and be reassured that disconnecting the battery from the motherboard will reboot your laptop, provided your circumstances are basically the same.
Thanks to anyone and everyone who commented on this thread, because your advice, trials & errors, and comments made it possible for me to fix my laptop. Thanks again and God Bless.