If you find your windows computer won’t start (The Blue Screen of Death) and it contains important data which you have not backed up, it may be possible to recover the data and then set about sorting out the computer problem. If the problem is a mechanical one with the hard disk then the whole disk could rapidly become completely unusable and the data unrecoverable. There are many data recovery companies who can often recover data from damaged hard disk drives but they tend to be expensive. One thing worth trying is to boot up your computer using the Linux operating system using a Linux liveCD and trying to access the data and copy it to an alternative storage media such as a USB pen drive or an external hard disk drive.
A live Linux CD contains the whole operating system on the CD and boots from the CD itself. You can download a liveCD from the Internet. If you don't have access to the Internet or don’t have a CD/DVD writer, you could get a copy from one of the Linux magazines which often include live CDs. Alternatively ask a friendly geek/nerd who will probably have several lying around.
Ubuntu is a common version of Linux that comes as a live CD and can be downloaded from the Ubuntu download website - click on the big orange "Start Download" button. You can’t just copy the files across onto a CD as the downloaded file is an ISO image of the CD. To make it workable this file has to be rewritten onto a CD or a USB pen drive. Follow the instructions on the Ubuntu download page under 'Burn your CD or create a USB drive'.
The next step is to get your ailing computer to boot from the CD. Many computers will already be setup to boot from the CD before booting from the hard disk drive. If this is not the case you will need to go into the BIOS and change the boot order. When your computer starts you will get a black screen with an option to 'Enter BIOS' - usually the f2 or del key. Press the key and the BIOS setup menu will appear. They all do the same thing but slightly differently (bit like peoples' anaesthetics really). You will need to find the Boot Order menu and change it so that the CD/DVD is the first choice. Once you've done that, save the BIOS configuration and restart the computer. As it starts you should get a 'Booting from CD/DVD' message, then a line that starts 'isolinux........'. The boot-up process can take several minutes so you will have to be patient whilst the computer loads everything from the CD.
Once the Linux operating system has been loaded you will need to find your hard disk drive and mount it (i.e. make it accessible)
Once mounted, it should appear on the desktop. If you also plug in a USB pen drive, that should also appear.