Sometimes the keyboard within BlueStacks is improperly configured for your country-specific keyboard. This is a known bug, where BlueStacks doesn’t correctly detect your keyboard layout. This causes the wrong characters to appear when you press buttons on your keyboard.
For example, the @ sign turns into a double quote on US-Standard keyboards.
To fix this, we have to modify the keyboard/language settings within BlueStacks.
Open up the BlueStacks home screen, and click the All Apps button on the top right of the screen. On the screen that appears, click the BlueStacks Settings button.
Next, click Keyboard Settings.
Under the Physical Keyboard section, click the first item. It has the name of the current keyboard setting.
A new window will pop up with the currently installed keyboard layouts. If yours is not on the list, click Set up keyboard layouts.
Deselect the wrongful layout, and tick the correct one. In my case, I had to disable the Dutch keyboard, and select the US international style.
To confirm your settings, press the Back button in the bottom left corner (yes, typical Android logic).
If you have selected the correct layout, you will now find that the keyboard works correctly within BlueStacks.
Finding the correct layout for your keyboard
If you don’t know what keyboard layout you are using on your computer, you can find out by clicking the keyboard sign, near the clock area on the bottom right of your screen. Or refer to this Wikipedia article.