Nothing on screen but computer still turning on?

Hello. I've searched around for this some but haven't been able to find specifically like I'm experiencing.

I have an older generation Macbook Pro (the all-silver two-part body style that came out before the current Macbook Pro) that I got approximately two years ago. I do use it quite heavily but have always taken good care of it.

About a week ago, I was using it as normal, then put it into sleep mode and went away from it for an hour. When I came back to it and opened it back up, there was nothing. I tried closing it and re-opening it, still nothing. I did a hard shut-down by pressing the power button until the power light went off, and then restarted it. Even though the computer turned on and the power light lit up, the screen remained black, and the Apple symbol on the lid remained unlit.

I called technical support and they ran me through a list of fixes including holding several keys down and turning on the computer, etc. None of them did anything to the computer as far as I was able to tell. I was not getting any sound, either--whether from having my computer muted or from the computer not working, I'm not sure.

I then tried putting the MBP into Target Disk Mode by connecting it to my sister's MB--no response. Still, the screen remained black on the MBP and no icon for the MBP Disk appeared on the MB. Even though the computer powers up, runs the fan and everything, it appears to be dead for all intents and purposes.

I have two main questions here:
1) What is going on here? Is it as simple as a screen problem, or has my motherboard gone? This is the very first problem I've ever had with my MBP; nothing has led up to this.
2) Is there any chance that my files are safe? I'm currently on vacation and backed up my files prior to leaving, but have done a lot of work since being on the trip and am not too keen to lose what I've done.

Thank you! Any and all advice is appreciated.