Can't change lock screen on windows 8.1

sfc and dism and chkdsk aren't going to do anything interesting here.  There's either an ACL or a registry corruption going on in between the lock screen settings page and the actual lock screen image repository.  SFC, DISM, chkdsk, and etc do not touch those and are pointless to try here.

I've seen third party advice about munging the applicable registry entries, but that's voodoo enough of a fix that I'm not going to repeat it.  A new user profile probably should not be corrupted in this fashion.

Sorry for my late response..

Once I click on a new background.. It just keep loading and finally does not load the image..

I tried the system file check and DISM both windows refused to open..

sfc and dism aren't windowed programs.  They must be run in a command prompt.  If you cannot run those programs in a command prompt, your system likely is too messed up to do anything but format and reinstall.  If you cannot run a command prompt, you may not have enough permissions to run one.  Or, NTVDM is installed incorrectly or corrupted (if you are using a 32-bit version of the OS on your machine).  Or, you've got some really ugly malware on it that prevents running any program that can fix problems on a computer. Or...?

Back up what you want to keep.  Can you run a command prompt as an administrator on your computer? If so, open one as an administrator (or Windows Powershell (Admin)), and then first run chkdsk c: /f /v /r and hit Enter.  When prompted to run it on restart, press 'y' and hit Enter again.  Following that, restart your computer.  This will take a while.  Find something to do while you wait.  It could take anywhere from 20 minutes to several hours, depending upon your hardware and size of your computer's hard disk drive.  Wait until the scan is done.

It will scan and may or may not restart the computer when finished.  Restart it anyway, after it is finished, and then try to run the sfc and dism commands again as instructed.  Neither of those programs will work if you have any serious file system corruption.  Chkdsk will find and fix what it can, and, if that was the first cause, you should be able to run the commands again and have them work.

Sorry for my late response..

Once I click on a new background.. It just keep loading and finally does not load the image..

I tried the system file check and DISM both windows refused to open..

Hi,

To further isolate the concern, do you receive any error messages when you attempt to change the lock screen image?

As a solution, we suggest that you run System File Checker and Deployment Image Servicing and Management tool to check the system. For steps, click here.

We look forward to your response.

Hello

My system lock screen has refused to change and i have done the best i can do to change it (including what you recommended).

Its a  HP envy 15 notebook PC

Please help