I was flashing nRF51822 used ST-link, with file hex from SDK example, so now i want flashing a different .hex. How can i do that? I try do like before but I CAN'T 


Hi,
We do not support openocd/st-link, so please ask their support channels for verification of the command line that you issue, but in cases where you cannot access the device, it is usually a connection problem.
Could you verify that you have connected the SWD lines correctly, and not chosen JTAG (we only support SWD) as the transport?
Kind regards,
Håkon