Hold the Shift key and press the number key 3. If hash symbol doesn't appear, then it seems like you have a UK keyboard layout. To change it, follow the instructions below:
Go to Control Panel (Classic View) --> Regional and Language Options
Click on Keyboards and Languages tab ---> Change keyboard
In "General" tab, click on Add --> Now expand English(United States) --> Under Keyboard, check the check box (Select) United States-Dvorak --> Click on OK.
Now in General Tab --> Set the Default input language as English (United States) - US from the drop-down menu and click on OK.
Now restart your laptop. After restarting your laptop hold the "Shift" key and press the number key "3".