c++ - Attach disabled display device with WinAPI -

my problem enabling disabled monitor changedisplaysettingsex. guess not rocket science after digging still looks impossible. found way disable secondary displays basing on microsoft code sample found here. while needed basic tweaking work, re-attaching never worked. trying was:

1. initialize displaydevice

bool            foundsecondarydisp = false; dword           dispnum = 0; display_device  displaydevice; long            result; tchar           sztemp[200]; int             = 0; devmode   defaultmode; zeromemory(&displaydevice, sizeof(displaydevice)); displaydevice.cb = sizeof(displaydevice); 

2. find devices

while (enumdisplaydevices(null, dispnum, &displaydevice, 0)) {     zeromemory(&defaultmode, sizeof(devmode));     defaultmode.dmsize = sizeof(devmode);     //point 3 goes here } 

3. detect detached device

if (!(displaydevice.stateflags & display_device_attached_to_desktop)) 

4. enable device

devmode    devmode; zeromemory(&devmode, sizeof(devmode)); devmode.dmsize = sizeof(devmode); devmode.dmfields = dm_position | dm_pelswidth | dm_pelsheight; devmode.dmpelswidth = 1920; devmode.dmpelsheight = 1080; result = changedisplaysettingsex(displaydevice.devicename, &devmode, null, cds_updateregistry, null); changedisplaysettingsex(null, null, null, null, null); 

last point returns disp_change_failed code , not enable display. did have similar experience?