PC Sound card issue: You observe following audio related issues.
I: No Sound, you do not hear any sound\audio.
II. Sound quality is very poor.
All these issue indicates problems with the sound card and problem could be following
> Outdated Driver: If sound card driver are not updated, please update them.
> Connections: Check if speaker is ON, headphone is connected properly and connected to green point on your sound card. Front panel audio might not be working or not connected from back side to motherboard hence use rear side audio point.
If nothing helps than contact your local computer technician.