I have a Samsung SyncMaster P2250 monitor that has worked for a year or so, but suddenly can't be detected by windows anymore. The monitor can display options and "check signal cable" messages. My GPU is a GeForce GTX 560, and I can use my second monitor just fine.
The primary monitor was connected via DVI, while my (currently using) secondary monitor is connected by a DVI-to-HDMI cord. I've switched between the 2 DVI ports on my Graphics card but that didn't change anything, and I don't know if it's a cable problem as I don't have any more DVI cables to test.
I've also updated my graphics drivers today.
EDIT: I tried hooking the monitor to another computer with a VGA cable and it worked, so it's capable of receiving a signal I guess.
More aboutmonitor longer detected windows
Right-click your desktop then click "Resolution". If it shows, set to "Extend". If not, go to your device manager and see if its detected there.
Device manager, Nvidia control panel, It's not detected anywhere.
Jeez, It could be your graphics driver, but I'm running short on ideas.
I updated my driver to try to fix it, but that didn't do anything. I think (and hope) it's just a problem with the DVI cable, I'll try a friend's cable to see. If that doesn't work I guess I could deal with VGA.
Alright. VGA isn't too bad, just slightly slower display. Try the cable your friend has and test it.