Dell Inspiron 1545, Windows 7 - cannot get Logitech LS21 speakers to work

Don't plug them into the line-in jack, rather use the line-out jack (the headphone jack).

Thanks for your reply.  I should have mentioned I'd already tried plugging into head phone socket, but it still doesn't work.  I've had a look at the settings, and theres nothing obvious that sticks out that I'm doing wrong.  When external speakers are plugged into the laptop via the headphone jack, and then i connect my earphones via the external speakers socket, sound comes out of these.  Any ideas?

Hi

Yes thats correct what you are saying above.  They were my mums speakers and they were working fine on her desktop computer last week.  I'll test them again at the weekend and see if they work on her computer. 

Thanks.

When external speakers are plugged into the laptop via the headphone jack, and then i connect my earphones via the external speakers socket, sound comes out of these.

Let me repeat that back to you so that you can tell me if I understand correctly. The external speakers are plugged into the computer's headphone jack, and the headphones are plugged into a headphone jack that is built into the external speakers? And you do hear audio through the headphones, but when you unplug the headphones you do not hear audio through the external speakers?

If all that is correct then the external speakers are defective.