According to Microsoft, DirectSound provides a system for capturing sounds from input devices and playing them through various playback devices.
Fix All DirectX Errors How to download and install all DirectX (Official)
Follow these steps in the order given to try the simpler solutions first.
Restart your computer if you haven't already. The error could be a fluke and a simple restart could fix it completely.
Install the latest version of Microsoft DirectX. The upgrade will likely fix the error 'microsoft.directx.directsound.dll not found'.