explorer.exe virus

[JoySkeet]

My explorer.exe does not start when i boot my PC , the key in  HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon  should be explorer.exe but it's empty , when i modify it to explorer.exe and restart my pc it goes back to blank  , it doesnt stay there , what can i do?  

[desertcomputer]

Restore to a given point or restore from backup or either reinstall windows. 

[JoySkeet]

I can't restore it because i installed windows from a USB drive , my original windows broke and i had to download a cracked one  , i couldnt even use my original key to activate it , so there's no restore point.

[Dabombinable]

8 minutes ago, JoySkeet said:

I can't restore it because i installed windows from a USB drive , my original windows broke and i had to download a cracked one  , i couldnt even use my original key to activate it , so there's no restore point.

Which version of Windows is it? I might be able to point you towards an .iso image that isn't from a disreputable source.

[JoySkeet]

You mean the windows i installed? It was 8.1 , then upgraded to 10 . No i'm using cracked version of 10 .. 

[Dabombinable]

1 minute ago, JoySkeet said:

You mean the windows i installed? It was 8.1 , then upgraded to 10 . No i'm using cracked version of 10 .. 

You have to get a non cracked, vanilla Windows 8.1 iso, then go through the entire upgrade process (I recommend making a Windows 8.1 installation USB, and a separate one for Windows 10).

This will help a lot with Windows 8.1: http://windows.microsoft.com/en-AU/windows-8/create-reset-refresh-media

Windows 10 media creation tool for afterwards: https://www.microsoft.com/en-us/software-download/windows10

[JoySkeet]

Woah..i have to reinstall again then update again..i'd rather start explorer from task manager..

[Dabombinable]

Just now, JoySkeet said:

Woah..i have to reinstall again then update again..i'd rather start explorer from task manager..

Cracked Windows=bad Windows. By creating the USB sticks you will save yourself time and prevent anything nasty from happening because of the bad copy of Windows.