I've had my Raspberry Pi for a few months now, and it's given me no trouble up to now.
First off, I use one of those micro SD cards that slides in to a small adapter that looks like a full sized SD, and it has always worked well in my Pi. I have an issue whenever I try to boot it up, a single red LED shows on the board and nothing happens, this is the same thing that happens when there is not even an SD card plugged in at all.
My temporary solution to this problem was holding the SD card to the board just as I plug it in, then when I see everything is working fine I just let go and it's good. Then, if I so much as bump that SD card everything turns to crap and I have to reboot it.
I really hope this is just a problem with the SD, which also has thin crack down the middle (I have no idea how this happened), because I could easily replace it. Although, the small crack down the SD card may not be a problem because everything is really stored on the micro SD card that just plugs into it. But also, I'm lead to believe that it could be a problem with the Raspberry Pi because when holding it the SD card down, as I described before, it boots up fine until that card is moved.
I did some research and apparently those small pins on the inside of SD card reader are broken easily. So please, any ideas about what the issue is and how to fix it?