The Laptop has a VGA output, so does the unknown TV have a VGA input ?
If the unknown TV has a Audio Line-in you can use an audio cable from the Laptop Headphone Socket to the TV.
If the above is not feasible you will need a converter box which are not cheap, or buy a new TV !
Though if you have SVideo out you could try a Scart Adaptor to output Video and Audio to the unknown TV:
Googling is quicker than waiting for an answer....