Each user account on a Windows operating system has a file named NTuser.dat inside. An NTuser.dat file contains registry settings and other information for an individual's user account. However, you can't open nor edit the NTuser.dat file using an application such as a text editor. If you want to modify the values inside an NTuser.dat file, you must use the Windows Registry Editor to do the task.
Click "Start," type "regedit" and press "Enter" to open the Registry Editor.
Highlight the registry folder labelled "HKEY_USERS" by clicking on it. The "HKEY_USERS" registry folder is located on the left-side of the Registry Editor.
Click "File" and select "Load Hive." Select the "NTuser.dat" file and click "Open."
Enter your Windows username or any other name into the "Key Name" field when prompted and click "OK."
Expand the highlighted "HKEY_USERS" registry folder by double-clicking on it. You will find the NTuser.dat file listed under it. You can expand the folder and subfolders inside the NTuser.dat file by double-clicking on them.
Right-click any registry key inside the NTuser.dat file and select "Modify." Change the values inside the "Value Data" field and click the "OK" button.
If you can't find the NTuser.dat file inside a Windows user account, you must unhide the system files on the computer. To do so, open Windows Explorer, click "Organize" and select "Folder and Search Options." Under the "View" tab, click on the radio button next to "Show Hidden Files." Next, uncheck the box next to "Hide Protected Operating System Files." Click "Apply" to unhide the NTuser.dat file.
Make a backup of the registry before making any changes to it. To do so, open the Registry Editor and click "File." Select the "Import" option and specify where you want to save the registry backup file. Click "Save" to backup the registry. Before exiting the Registry Editor, you must unload the NTuser.dat file. To do so, highlight the name of the NTuser.dat file. Next, click "File" and select "Unload Hive."