how to enter emergency mode

Hi everyone I need to Merge storage spaces but I don't know that. plz anyone help me?

Hi, My system rebooted suddenly then there's no network connection.... can't be accessed. due to Video card has been set to VFIO, so there's no display , the only way to access is network but it is down.... is there any way to boot to 'emergency mode' to by pass the vfio configuration or other...