Something happened to my Optimus One

[asdjklghty]

Earlier this morning, my Optimus One didn't recognize the SIM card and all my apps on the microSD card weren't on the SD card and it shut off. I tried to turn it on until I charged it to give it some juice (it was like 2% when I plugged it in) and after it charged, I unplugged it and the phone turned on. Back to normal. Weird. What happened and how do I prevent this from happening again?