Can't boot Windows 7. No hair left to pull out.

This morning I powered up my Windows 7 64-bit desktop and received the message that it I needed to insert the boot device. It normally boots from the hard disk. I inserted the repair disc and tat put me into a loop whereby it would "repair" the system, reboot, and bring me right back to the system repair screen. After several "repairs", the system was no closer to being resolved. When I removed the repair disc it rebooted back to the insert boot device message. When I hit F10 I noticed that the hard drive was not first in boot priority, which I corrected but to no avail.

I would like to try to reinstall Windows on this machine. I don't have any Windows discs but I do have the product key. My laptop is running Windows 8. Is there a way to download Windows 7 onto a CD/DVD on my laptop then use that disc to reinstall it on my desktop? Thanks.

Thanks. I will try it

Thanks for the replies. Unfortunately the problem is worse than I thought. I was able to get a hold of an install disc. It asked me where I wanted Windows installed but refused to acknowledge any hard drive on my machine, instead telling me load drivers. Of course I don't have drivers for my hard drive, nor have I ever seen any such thing on the net. Any advice? Thanks.

Thank you. My machine is an unbranded HP refurbished that came at a good price if not a good value. I will check out you solution and thanks for offering it.