I can’t Load my computer

I was scanning for hard drive failures and mid-way through the scan, My computer started freezing and returning then freezing again, until I thought it restarted. Now, I can’t start up my OS. and I tried setting the 1st boot device to hard drive or to ATAPI CD-Drive but no luck. I couldn’t access anything. Even if I put a CD inside it, it tells me to reboot or insert a media device and press anything, but no luck. It keeps asking me that. I couldn’t access my hard drive or my CD-drive hence, I couldn’t do a reformat. What do you think happened and how do I install a fresh OS? and is there any way to recover the files in my old hard drive?
edit:
My MoBo: ASUS P5QPL-AM if it helps.. please help me cause I really need it badly..
I inserted the Windows 7 DVD that I used to install windows 7 on the same ccomp before, however this time, it won’t load the CD.. just keeps telling to rebood and select preoper boot device or insert boot media and press anything.. however I tried both and none seem to work.. help please.
Answer #1
Make sure all your ATA devices are on cable select settings (if you have ATA hardware still) and then on your motherboard pull the battery out of its sock and leave it out for 10 minutes or so. make sure your power to the main computer is also unplugged from the wall. Put the battery in and let your computer scan for devices. After it is done, restart and try to boot from DVD again.
Answer #2
Try to change jumper on cd or put cd and hdd in separate ide cable,if both are master or slave you will receive this error. Check if ide cables are connected,see jumpers jumper on hdd must be master and jumper on cd must be slave.
Answer #3
I got it solved already.. thanks for the reply guys.. I dunno what the heck happened but I just opened the case and replugged/tightened the plugs to my hard drive… I dunno what happened though and what it had to do with me checking for hard drive errors..