If you prefer a graphical interface, you can configure the standard Windows Features menu to look for local offline files.

: Open "This PC" and check the drive letter assigned to the mounted ISO or USB (e.g., Step 2: Use the DISM Command Search for in the Start menu, right-click Command Prompt , and select Run as administrator Type or paste the following command, replacing with your actual drive letter from Step 1:

To confirm that the .NET Framework 3.5 is running properly on your Windows 10 system: Press the to open the Run dialog box. Type optionalfeatures and press Enter . Look at the top of the Windows Features list.

Right-click the downloaded file and select . Follow the on-screen prompts to extract and install the framework components.

Open Command Prompt as Administrator.

If you are on a metered connection, lack internet access, or need to install this on multiple machines, using a is the best solution.

If the box is filled, you're all set!

If you do not have the original Windows 10 installation media, you can download the standalone runtime package from a connected device and transfer it to your offline 64-bit machine.

Save the dotnetfx35.exe installer file to your storage drive. Step 2: Install via Command Prompt

: Right-click your ISO file and select Mount , or insert your Windows 10 USB drive.

If you want, I can provide the exact DISM/PowerShell commands tailored for your drive letter and Windows build.

You must log into an account with administrative privileges to modify Windows features.

Once you've finished the command-line process, it's always a good idea to double-check your work.

The process will take anywhere from 2 to 10 minutes. You will see a progress bar. Once it reaches 100% and a message states "The operation completed successfully," you're all set. Close the Command Prompt and restart your computer if prompted.

Press Windows Key + R , type , and hit Enter .

Wait for the progress bar to reach 100%. You will see a message stating, "The operation completed successfully." Method 3: Using a Third-Party Offline Installer Tool