MacBook Pro Monitor Issues and Resetting PMU

The screen on my older (four years now) MacBook Pro 15" recently stopped turning on. It SEEMS like the laptop is working normally underneath (volume buttons make noise and shut down is capable with power button then enter). Also, if it helps, the Apple on the back of the cover also doesn't illuminate anymore. And I couldn't see anything when I tried to manually backlight the screen. I haven't had access to an external monitor yet to see if it shows up on that.

Anyway, I've heard a lot about resetting the PMU for these types of problems, but I wanted to make 100% sure that I wouldn't lose any data if I did that. Sounds like I wouldn't, but I want to be extra safe.

Furthermore, does anybody have any other suggestions for a problem like this? Thanks!

Here's a list of things to try.

Suggested fix to black display from applecare.
Unplug power, disconnect battery, hold down power button for 5 secs, reconnect battery and power, restart. This resets the power manager. Reseting PRAM has been suggested also.

* The PMU reset procedure, described above, seems to work only sometimes and not for long. This is the procedure that will help you (have done it, and no problems for a week):
o Go to Energy Saver options at System Preferences.
o Set display sleep time to 1 min.
o Let the computer put the display to sleep.
o Go back to normal use, and set the display sleep time to the desired value.

All set, it will probably solve this issue.

* Possible loose connection.
Pressing down with moderate force between the keyboard and hinge on the left-hand side about one inch from the edge may engaging the LCD. This was confirmed through Apple Care when the user established that all other functions worked by using a second monitor and alternatively pressing and releasing that seemingly arbitrary location. Tech support indicated that the power connection for the LCD is located in that area.

Thanks! The PMU reset ended up working for now... If it goes out again I'll definitely keep your other suggestions in mind. The thing about the connections being disrupted was especially interesting.

Thanks again!