my till when i turn it on just say's closed tried pressing clerk buttons bu?

This sounds like a Samsung, but I haven't heard of this model. Samsungs require a clerk login before they will remove the "CLOSED" from the display. You either press CLERK1, or CLERKA, or 'A' button, or if you have a code type of clerk system, press1, then CLERK.

If you need a Samsung manual, there are some here
http://the-checkout-tech.com/manuals/cashregisters/samsung1.php

Mark
February 2010