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Windows 7: I broke the logon screen (tried to replace the system file.)

24 Sep 2013   #1

I broke the logon screen (tried to replace the system file.)

I hope this is the right category for this thread, apologies in advance if it's not.

So I was trying to replace the logon screen's system file, "authui.dll" with a custom file, I broke my computer's logon screen in the process. There's just a blank screen with a cursor in place of the logon screen, so I can't log into the computer to do a system restore. I can't even log into safe mode.

Maybe when I saw the lock icon on the system file I shouldn't have attempted to switch users just to test it.

A clean install is not an option (Unless I can access all my files from another computer and save them to an external drive frist.), I have all my important files on this computer. I should've thought about this more thoroughly.

I don't have a windows 7 disk for system repair, could I do it with a USB stick? (And would my files be safe?)

I'm not sure what I should do here.


My System SpecsSystem Spec
24 Sep 2013   #2
Microsoft MVP

Windows 7 Ult. x64

On another Windows 7 computer create a system repair disk using this guide:

System Repair Disc - Create

Then attempt a system repair on your computer using this guide:

Startup Repair
My System SpecsSystem Spec
24 Sep 2013   #3


Thanks for the tip. Will my files be safe this way?
My System SpecsSystem Spec

25 Sep 2013   #4


Thanks for your help, I finally managed to create a USB from the proper Windows 7 install. But the normal Startup Repair that you suggested doesn't work with what I'm trying to repair. Here's what the guide said:
"Startup Repair will not repair unbootable systems caused by the following issues:
  • Malfunctioning firmware and other hardware components
  • Problems with clean Windows installations or Windows upgrades (for example, from Windows XP to Windows Vista)
  • Windows logon errors
  • Viruses and malicious software"
I have no idea how to use the command prompt so I would need specific instructions on how to fix the system files, specifically the "authui.dll" file that I broke, I know it's this file specifically because I was messing with it. Do you know how to do it?

I would feel much safer being able to plug the hard drive into my desktop and extract my important files from the drive then doing a fresh install. Especially because using the command prompt was one of the reasons I broke my operating system in the first place. (I have no knowledge of coding.) I tried plugging the drive into my desktop to do this, but I can't see the drive. How do I see the drive and it's files to extract them?

Thanks for the help.
My System SpecsSystem Spec

 I broke the logon screen (tried to replace the system file.)

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