If it’s a desktop, the problem could be as simple as a cable coming loose. If it’s a laptop, perhaps the battery is no longer seated correctly. Don’t panic until after you’ve tightened some wires.
The Windows Safe Mode loads the operating system with minimal options. This works without loading external or installed drivers. Restart your computer. Press the F8 key, while it boots, to get to the Boot menu. Choose Safe Mode from the Windows Advanced Options Menu. If you’re on a Mac, power your system down completely. Hit the start button; after the first start-up tone, hold the ⇧ Shift key until you see the Apple icon. You’re now in Safe Mode. Booting into Safe Mode and performing a clean shutdown–or a restart–will help.
This option is available on the Boot menu you’ll see after hitting F8. The full text is Last Known Good Configuration (your most recent settings that worked). This will start the PC using the last working version of the Windows registry. It doesn’t delete anything.
Use System Restore to roll-back Windows to an earlier time when everything worked properly, to reverse the effects of bad software or drivers Set a System Restore point when things are working well. In Windows, by default, one is created for every installation. Create a new restore point manually before you install anything or make major changes to your PC. Type “create a restore point” in the search box on the Start menu. Click the Create button at the bottom of the dialog box. Give the restore point a name and wait a few seconds as it’s created. For actual restoration, go to the System Restore via the Control Panel. Pick a point and start the rollback. Note that this doesn’t impact your data, such as documents, music, photos, etc. This is all about getting your software, drivers, and OS back in a working state. However, you can right click on a file or folder and select “Restore previous versions. " There’s a chance something might get restored if it was part of the System Restore shadow copy.
From Windows Vista, Microsoft got rid of the Recovery Console and replaced it with the System Recovery Options menu. Reboot using the CD and select “Repair your computer” to get to the toolbox of options.
There are some other outside options that do similar job. NeoSmart’s Windows 7 System Recovery Disks (If you’re still using XP, look at Build an XP SP3 Recovery Disc). There are also a number of Live CDs. Basically, these are Linux installation discs. The OS can run from the disc itself, or from a USB flash drive. Use a Live CD for a distro like Ubuntu or Knoppix to gain access to your hard drive when Windows goes down, so you can, hopefully, recover files.
These free versions, which usually use some version of Linux to boot into tools, are better than nothing when faced with a particularly virulent payload.
The safest and cheapest is to invest in some data recovery software. There are plenty of options: GetDataBack, Stellar Phoenix Windows Data Recovery, EASEUS Data Recovery Wizard, and many more. Many of these programs are great for getting deleted files back from the dead.
