Cant extend display over 2 monitors

[SamDaGladiator]

i am running 2 gpus not in sli which are both recognised by the computer and i have a cable in both gpus to the monitors. this has worked for around a year, when booting up this morning the display went back to one and at the lowest res. when i try to change these settings it says 'unable to save display settings'. what should i do?!?

Error: http://prntscr.com/a8nofa

 

[SamDaGladiator]

i tried plugging the monitor with a hdmi rather than a display port and it worked. do display port cables just break when they are being used?