So yesterday I was using my Pi 3 when the power went out. I wasn't really worried, I just unplugged the Pi, turned the power back on, then waited for about 30 minutes, and then turned the Pi back on. And then I wasn't getting ANY response. The green light wasn't flashing, my TV said "No signal detected" and so I thought that I didn't plug in the HDMI properly. So I unplugged it, plugged it, and turned the Pi on (again). Same thing happened, so I decided to install NOOBS again. I deleted all Pi partitions, created a new one, set it as active, formatted the SD card, etc... When I plugged the SD card back in the Pi and turned it on, nothing happened, just the red light turned on (like before). BTW I already had the newest NOOBS version installed. What do I do to make it work again?
I had to format my SD card again now with the SD card formatting program. From the moment I turned the Pi on the green light immediately flashed, and it started booting up. Thanks to goldilocks.