BAU Password reset

Sir we have 1 project for KNX schneider for LCS where we are doing maintenance. Currently we are trying to reprogram the devices e.g sensors & actuators but when we download application, a pop-up window appears with BAU password... we don’t have any password. And the contractor who have done this project did not handover any password. Currently we can not reach the the contractor. so how we can reset the BAU password for devices?? Or is there any way to master reset the device. Please help