Greetings, Andy:
Firstly, when you say Restore Disc, do you mean a set of OEM Recovery Discs that will allow you to do a complete factory restore, or do you mean a Windows File History backup on a CD-ROM?
When you start your computer, do you get any reaction at all, or is it completely dead? If you get video signals and the HDD is running, then hit the BIOS activation key (usually DEL, ENTER or F1/F2) continuously - and frenetically!
Alternatively, try to remember the key to set a temporary boot order (usually F12). If this doesn't work, but the machine is still running, open the DVD tray and insert your Recovery Disc if you have one. Restart the system. If this doesn't work, the machine is practically dead, but still recoverable...