Change user account picture

It's possible that there's some group policy preventing this. Talk to your sysadmin. Potentially your cached local user account could have something corrupt as well.

I hope it's ok to answer this old question, but it was the first thing I found when searching for it, so I thought it might be helpful to others to try what worked for me.

Another thing you can try if you feel comfortable with using RegEdit. (this can, of course mess up your computer, so use at your own risk).

1. Open Regedit. (either search in the startmenu or select Run... and type regedit)
2. Search for any occurrence of UseDefaultTile ( should be: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion‌​\Policies\Explorer\U‌​seDefaultTile )
3. For each, make sure it is set to 0 instead of 1.
4. Close the Registry Editor and check if you can change your icon.

This will obviously change it for any local policy available on your computer. If you want to change it only for specific policies you will have to check which you are changing first.

Note: this will only affect local accounts. For Group / Domain policies you will most likely need to change the domain settings on the server.

ALTERNATIVE: Change default user account picture

You can change the default user picture, but that will mean every user will have the same picture, which is probably not what you want.

1. Create or resize a picture to 128*128 pixels and save as .bmp to avoid cropping
2. Save the picture as "user.bmp"
3. Navigate to \ProgramData\Microsoft\User Account Pictures (ProgramData might be hidden, depending on your Settings, should be on your main boot partition though.)
4. Rename the user.bmp to something like user.bmp.bak so you have a backup.
5. Copy the previously created picture to the folder (requires admin priviledges)
6. Press Windows + L on the Keyboard to test if it worked.

Hope this helps.