i have an hp pavilion s7210n slimline
and my mom said she's pretty sure its an on board not a stand alone
Its an HP. That means it comes with comprehensive hardware diagnostics that test all hardware provided by HP - including the on-board sound card.
Windows should load drivers automatically. But will not if hardware is defective. Is your problem in Windows or with hardware. Current you do not know. And this is exactly why better computer manufacturers provide those comprehensive hardware diagnostics for free.
Diagnostics can be booted from the hard drive, may have been provided on a CD-Rom, or can be downloaded from HP's web site. If the soundcard passes, then problem is in Windows. If soundcard fails, problem may only be a setting change (such as from digital to analog output).