If you forgot your Windows admin password, try this
All is not lost. You just have to wiggle the lock on the virtual back door.
By Ian Paul and Lincoln Spector, Contributing Editor, PCWorld
Okay, so you forgot your password for logging in to Windows. All is not lost. You can still log in to Windows—even if there is no other administrative account on the PC.
From a security point of view, this is actually scary news. But there are legitimate reasons to use the tricks below, and none of them will let a criminal log in without your knowledge (the password is changed, not revealed) or gain access to encrypted data. (You do encrypt your sensitive files, right?)
I’ve provided instructions here for Windows 7 and 10. Windows 8 users should have no trouble following the Windows 10 instructions.
Microsoft Windows 10 Home | Download
You’ll need a Windows 7 System Repair Disc. You can use one created on someone else’s Windows 7 PC—providing that one of the PCs isn’t 64-bit and the other 32. You’ll find instructions for making one in my Boot discs explained article.
To change the password, boot from the System Repair Disc. When prompted, press any key.
Eventually you’ll get to the System Recovery Options screen. Note the operating system location; it might be C:, or D:, or whatever. Click Next.
At the next page, click Command Prompt.
Once there, type each of these lines, pressing Enter after each one. Replace the x in the first line with the operating system location you noted above.
ren utilman.exe utilhold.exe
copy cmd.exe utilman.exe
Remove the disc and reboot.
At the log-on screen, click the Ease of access icon in the lower-left corner to bring up a command prompt.
Within that command prompt, type net userusername newpassword, replacing username with your current username (it’s clearly visible on the screen), and replace newpassword with—I’ll leave that up to you.
Finally, close the command prompt and log in with your new password.
Your Windows 10 user account is almost certainly connected to your online Microsoft.com account. This makes replacing a forgotten password easier—and arguably more secure.
On another computer, go to Microsoft’s Sign in page. Once there, enter your email address and click Can’t access your account.
Then follow the wizard. You’ll have to prove that you really are you, based on answers and phone numbers that you’ve previously provided. Eventually, you’ll be asked to create a new password.
That technique won’t work if you took the pains to create a local account. In that case, use the Windows 7 instructions above, with these exceptions:
Boot from a Windows 10 Recovery Drive and use that to get to the command line. You’ll find the instructions in my Windows 10 Safe Mode article.
The ease of access icon is in the lower-right corner, between the Power and Connect to Internet icons.
This article originally posted on October 16, 2015, and has since been updated.