Hi,
· From every application are you getting the low sound or from any particular application?
Method 1: I would suggest you update the driver for the sound card. You can also download and install the latest sound card driver from the sound card manufacturer's website:
http://windows.microsoft.com/en-US/windows7/Update-a-driver-for-hardware-that-isnt-working-properly
Method 2: You can also follow the instruction provided in the following link and check if helps in fixing the issue:
http://windows.microsoft.com/en-US/windows7/Tips-for-fixing-common-sound-problems
If following above mentioned steps does not resolve the issue, I would suggest you contact the manufacturer for the same.