Helping people with computers... one answer at a time.
If your machine won't boot for some reason, there are several approaches to try to get the data off of its hard drive. I'll examine a few.
I have Windows XP; it does not startup right away. I have to shut it down and open it several times until it works. It just hangs after the Windows logo and you feel you can work with it, but nothing's there. You can move the mouse, but there's no connection. It is a completely frozen PC. Today, it does not want to start or to work at all.
I have files that I want to save before I can format it.
At the risk of annoying some of my regular readers (who'll know exactly where I'm heading with at least part of this answer), I wanted to address this for one simple reason:
It's oh so common.
A dead machine, with important files on it.
In fact, the dead machine is the only place that those important files happen to be.
I'll look at a few ideas on recovering those files, but perhaps most importantly, I need to make sure that everyone learns an important lesson from this situation.
My first course of action would be to perform a repair reinstall of Windows from the original installation media.
A repair install essentially re-installs Windows in place without affecting installed programs or settings. It's somewhat like "upgrading" from one version of the OS to another as it goes through many of the same steps, except that you end up with the same version of Windows that you started with.
Simply boot from the installation CD, select "To set up Windows XP now" (not the repair using Recovery Console option), and accept the license agreement. You'll get the option to repair an existing Windows XP installation shown above.
If Windows can't be repaired, then our priority changes to salvaging the data from the hard disk before reformatting and reinstalling the operating system from scratch.
One approach is to use what's called a "Live CD", a CD (or DVD) image of an operating system that simply boots and runs entirely from the CD, without requiring the hard disk and needing to be installed on the hard disk.
Ubuntu is a good Linux distribution to use for this purpose. Boot from an Ubuntu Linux distribution CD. If it asks, make sure to select "Try Ubuntu"; you do not want to install it.
Once booted, the Live CD operating system allows access to the contents of the hard disk, USB devices, and often your local network, so you can copy off the files that you want.
In some cases, one expeditious approach is to actually physically remove the hard disk and install a new one in its place. You can then install Windows safely from scratch on the new disk.
You can then install the old hard disk as a second disk in that machine, install it as a second disk in another machine, or place it into an external USB enclosure so that it could be connected and accessed from any machine.
Once that old disk is accessible, you should be able to access all of the files that you need.
The lesson to learn is simply this: there'd be no risk of data loss if your data had been backed up.
I know that I harp on this a lot, but it really is the one thing that you can do that can save you from almost any failure.
If your data exists in only one place - for example, if it's only on your computer's hard drive - then it's not backed up. You risk losing everything, permanently.
In a case like this, we can likely recover your data using one of the approaches above, but you can't count on that. A hard disk failure - and they definitely can and do fail - can render all of the information on your hard disk unrecoverable.