Monitor speakers not working windows 7

Hello,
I have a neighbor who has an HP monitor with internal speakers. Her PC crashed last week - her son re-loaded all back to working condition. Two days ago, her speakers went "dead". I checked the connections, volume levels etc via control panel functions, even checked to see if the driver(s) needed updating (which they didn't). I was going to by-pass the internal speakers and try a set of external speakers to see if that worked.Stumped as to next step. Please advise...