Hi! Does the machine chime or beep when you power it on?
First I'd try holding down the option key as you boot up. If the option menu appears, this is a good sign, and may just mean that the laptop can't find a bootable volume. In this case, I'd try booting from the restore media, and see if it will let you reinstall the OS. The default settings will not erase data on the drive. If the screen which asks you to select a drive to install to does not show any drives, pull down Disk Utility from the top of the screen, and see if it lists the hard drive when the utility appears. If it does, run a disk check on it to see it that reveals anything, and then format the drive and install the OS.
If the laptop doesn't chime, or option mode doesn't appear, I'd try resetting the PMU first and then the PRAM. If that doesn't help, I'd reseat the RAM, and try powering on with only one module installed, and then switch slots, in order to test for a bad slot. A bad slow populated with RAM will generally cause the machine to not boot.