Definitely via Swidnica, you'll ned to check the timetables at the Sobotka bus station for routes to Swidnica, then catch another bus at the main station to Walbrzych. Wroclaw and then back to Walbrzych will add around 35 miles to the journey, buses will not be a problem, there will be plenty of regular routes most probably every hour.
You would be able to access bus times from the PKS number.