No picture says in power save mode

This can have multiple solutions so heres a few:

• The graphics port went bad, try hooking to a monitor known to work

**If the port is bad most desktops have several options for PCI slots to install a new graphics card

• The input on the monitor is wrong , for example if you're connecting HDMI bur the monitor is on VGA
• The power supply or other internal component could be bad

I would first try hooking it up to a 2nd monitor/TV.

try checking the computer and seeing if it iis awake or if the monitor is connected to the right port.