The actual restoration (not to be confused with System Restore) is very quick and easy because the restore image is on the hard drive if you got the computer new from Dell. If it is used then someone might have removed the restoration partition from the hard drive, or the hard drive itself might have been replaced. In that case you would have to do a manual re-installation of Windows from discs and it might be easier to just return the laptop. See instructions for restoration here. It also has instruction for System Restore and other related operations. After restoration  test the audio immediately before updating anything. If it is fixed then proceed with caution with updates. The old-school advice about updates is if it ain't broke don't fix it. Mainly this applies to Microsoft. I only let it update security and the OS itself, not drivers.