my second monitor(dual screen) stopped working

[zniff]

i woke up this morning turned on my computer and my second monitor didnt display anything ive tested the ports nothing wrong there. tried to test on another computer not very satisfied but i understood it didnt work there either.
i get the square with "check signal cable"
only thing i can do at the monitor is tinker with the PC/AV mode only i cant select any of the choices

 

[ThomasJ93]

Did you also check it with a different cable? If it doesn't work with that either, I'd say it's broken, so return it to the retailer.

 

[zniff]

tested the cable, and its nothing wrong with the cable

 

[ThomasJ93]

Then the display if faulty. If it has multiple inputs, you could try another one.

 

[IvorTollah]

I had the same problem, I'm using a Lenovo B50-80. After trying everything you mentioned above I wen't on to the Lenovo website and downloaded a BIOS update tool. Once the BIOS update was done the second monitor worked. I'm not sure what system you're running but if you can go on to their support site and download a BIOS update tool then that might work for you.