Thank you so much Brink for your quite a good tutorial. But I have applied all the steps and I restart my computer. When the windows booted again, I have found this message :
It is in Arabic, but I would like to translate as far as I can: this message say that 'System Restore' 'wasn't successfully completed and the system files and settings of the computer weren't changed.
The System Restore failed in replacing(extract) the file "C:\Windows" with its original copy from 'System Restore'
An unspecified error occurred during the process of the System Restore (0x80071a91)
You can try to do the 'System Restore' again and choose a different restore point. If you continue to see this error, you can try an advanced recovey method can take another restore.