Having the whole operating system on disc isn’t necessary if you just need to repair your Windows installation. Recovering or repairing your current installation of Windows is favorable cause most recovery software that comes with brand name PCs will wipe your PC back to factory settings. You should have a repair disc on hand to deal with the following situations:
You’ve made a change to your PC and it now won’t boot into Windows You get a message such as NTLDR is missing but your hard drive has not failed You get a virus on your PC and need command line access to fix the issue Windows starts to boot and then your PC power cycles