I need a code to unlock my garmin 760 gps that i bought

Cathy, what follows below is cut and pasted from a Garmin tip I wrote for your problem:-

"You have Garmin Lock activated on your nuvi: there are only two ways you can unlock it.

1. Enter the PIN code (but you clearly don't have it).

2. Take the unit to the Security Location you chose when activating Garmin Lock: it will then unlock without the PIN code and you can then either reset the PIN or disable Garmin Lock. The Security Location should not be the owner's home address, but many owners ignore this recommendation. Many owners choose their workplace or a close friend or relatives address for this purpose.

If neither option works then your unit is useless unless you send it to Garmin with proof of purchase. Garmin charge for the service and if your maps are not up to date then it's really a waste of money as the investment would be better spent on a new unit with current mapping.

I hope that you manage to either fix your problem using my advice or at least can decide whether to abandon the unit and buy another."

So to summarise, unless your seller knows the PIN or unless the seller can take the unit to where Garmin Lock was set up in order to deactivate it for you, you have purchased a useless brick, sorry.