When you start your computer, tap the F8 key (F5 on some models) and run your computer in Last Known Good Configuration or in Safe Mode.
The PC boots into safe mode with networking
If, despite the restoration, the PC can boot into safe mode but not normal mode, there is probably a hardware or software conflict or infection, if you recently installed software or hardware to uninstall see if your computer starts normally. Then try to scan your computer with your disinfecting software (antivirus ...) as well as online antivirus.
If the PC still does not start normally:
download LogonFix and run the executable and that's it. (Nothing happens on the screen, no confirmation) and then restart the PC normally.
(Version XP and earlier only)
To use a boot disk, you must start the computer from the floppy disk (if necessary configure the BIOS putting floppy / disk in the first position and not CD).
Repair from command prompt
Note the spaces between certain characters, if you forget the command will not work.
If the Windows disk containing the C: drive
chkdsk c: / f / r
and is validated by the "Enter" key. If the drive was to analyze is e we would typed:
chkdsk e: / f / r
When the repair is completed the command prompt returns to its home line. Type "Exit" and press the "Enter" key to exit
Use the repair console under Vista / 7
If your operating system is Vista, download the repair console for Vista.
If it is Seven, download one for Seven.
Use Antivirus Live CD
If you suspect the presence of a virus, Antivirus Live CD containing start directly from the CD without using Windows, to scan your computer and eliminate infections. You must start the computer from the CD by changing the boot order in the BIOS.
Connect the hard drive to another computer or add a disk to the computer
You can connect your hard drive to another computer, Slave drive in a docking station, or external drive with a USB adapter, and so fetch your data and try to repair it (disinfect, delete software, drivers ...)
To repair a Windows drive, go to Computer (desktop) and click the right mouse button on the drive to repair, then go to properties, then in the Tools tab and Error Checking
To disinfect analyze the disk with your antivirus.
Otherwise, you can add a new hard drive in your computer where you install Windows or Linux. You start over and try to recover data from the disk (infected ...) placed disc "slave" or USB.
You can then format the disk and reinstall your operating system or restore it if it has been repaired (disinfected ...)
If you made an image of your system with windows or software like Norton Ghost, Acronis true Image DriveImage XML ... you can restore the pc from the image. But all data not saved after that image will be lost unless you saved them on other media.
Warning: reinstalling Windows will erase all personal data on the formatted partition.
If you have multiple partitions and you are in a format to reset Windows, only that partition is deleted, the other is intact but may still contain infections.
Note: If you have formatted your computer without recover all your personal documents, there is software to try to recover your data.