Camera offline

Hi, I have a security cam which has just gone off-line, installed about 18 months ago been working fine. I have reset the Router, this is working fine because I can see it with my phone, I have also checked the power and the lights are working but the camera is not, i've been through all the troubleshooting and got to the bit where it wants you to press the device for 15 seconds I have done this and the camera is not flashing, it's not responding at all.....any idea?