ok so when i boot up my computer it says windows had failed to start. so how can i run my system restore disk? please help!

the make and model of your computer would be a great help but generally speaking insert the disk and re-start your computer. if you don't get the option to boot from the disc go into bios (F1, F2, F10 or DEL depending on your computer) and make your cd/dvd drive the first boot device.