Попытаться получить доступ в командную строку (Безопасный режим с поддержкой командной строки) и выполнить операции с реестром:

REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v Shell /t REG_SZ /d Explorer.exe /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v Userinit /t REG_SZ /d userinit.exe, /f
REG DELETE "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe" /f
REG DELETE "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe" /f
REG DELETE HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /f
REG DELETE HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /f
REG DELETE HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /f
REG DELETE HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /f
REG EXPORT "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" C:\Winlogon.txt
REG EXPORT "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options" C:\ImageFEO.txt
REG EXPORT "HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot" C:\SafeBoot.txt