Hi,
1. Did you make any changes to the computer before the issue occurred?
rthdcpl.exe is a process belonging to the Realtek HD Audio Control Panel and is bundled alongside Realtek sound cards and audio hardware.This program is a non-essential process, but should not be terminated unless suspected to be causing problems.
I would suggest you to uninstall and reinstall the sound card driver from your computer in Device Manager.
To uninstall from Device Manager, follow the steps given in the link below:
a. Click Start.
b. Right-Click Computer.
c. Click Properties.
d. Click Device Manager on the left hand side.
e. Right-click on the sound card driver.
f. Click Uninstall.
g. Follow the prompts to continue to uninstall the Driver.
Once uninstall restart the computer, after restarting by default the driver will install it successfully, if not try to install it from manufacturer’s website.
Hope this information is helpful.