I had my laptop on, and the battery was 100%. I was going to leave it on working for a while, so I plugged it into a power outlet (not equipped with a surge protector) at a friend's apartment. It immediately shut down everything. I was unable to get it to start up again, whether or not I just used the power cord of mine or of my friend's Hp laptop, and whether or not I used my or my friend's battery. I have tried holding the power button for thirty seconds with it unplugged, plugged in and with the battery out and in. Nothing lights up or shows any signs of life. What happened? Any clues for how I get my laptop back??? Do you think even if the laptop is gone could i retrieve my files (I didn't have them backed up unfortunately)

You should be able to retrieve the files. Either take out the drive and get adapter or usb enclosure to attach drive to another computer. Kind of difficult to tell.Nothing seems to jump out as to where to look. I suspect that the power module has gone bad. As you say it was on and dropped out, no sign of life, Might be time to think about a new one. They are never cheap to fix unless you have line access. (and who does anymore) As a rule you never leave the battery in a laptop if you have it on AC. It will save battery life and use less power. (per IBM). Playing to the angels Les Paul (1915-2009)