A boot disk is an important tool for computer-failure emergencies. The boot disk is essentially a CD that contains a few files that are integral to a computer's boot process. This means that if your computer suddenly fails to boot becaues of file corruption, virus or any other problem, you can insert the boot disk and the computer will read the files from the CD and boot, and allowing you to troubleshoot and fix that problem.
1. Open the "C" drive (or the main drive if yours isn't labeled C by default) and then find the "I386" folder. (check whether this files are not hidden in: my computer->Tools->Folder options->"View" tab->Under the Hidden files and folders "Click" show hidden files and folders->OK)
2. Within this folder are three files you must copy to a CD to create your boot disk, the three files are Ntldr, Ntdetect.exe and boot.ini and write this files to that Blank CD.
This CD will help in most of the Computer emergencies.