Flashing ?, check. Install Disc 1 with "c" or "d" only ejects disc

Mid 2007 machine: Dropped from three feet onto tile floor. Was in sleep mode at the time. Picked it up and logged on bringing up the Internet it seemed fine. Shut down. Upon restart, flashing ? folder appeared. Tried resetting the pram. Tried booting the install disc 1 under the "c" and "d" restarts. The disc spins a bit and then ejects. Could be making a sound from there too, but its slight and uncertain about the sound. In any event, I replaced the hard drive and conducted each of the above with no change in result - that being ejecting the install disc and giving me a flashing ? screen. Also, note that when the magsafe power is put in, it doesn't glow (as it would green if charged and yellow if charging). Please advise. Thanks

Thanks for the first reply! Sounds pretty good, but I can't get an option for startup. If I try to startup from disc, the install disc 1 for example, it just spins that install disc for a bit and ejects itself, giving me the ? screen and there's nothing on the gray screen until it ejects. So its as if I can't even deal with the HD issue yet. Additional thoughts?