Display options problem

Hi. I have a strange problem and not sure how to fix it. I have a destop acer aspire z5761, i have it nest to my hd 42 inch tv. Until today i have been running a dual monitor with no problems. However today the display on the tv which is usually fine went blank. I was able to see my desktop background but nothing else could be dragged onto it. So i did a system restore and this is where it gets odd, my computer decided to change the main display to the tv rather than the monitor, this wouldnt normally be a problem however now when turning on my computer with the cable for the tv inserted the display only appears on the tv screen and leaves my monitor blank. However the cursor is on screen but cant be moved and no key strokes work so i am unable to do anything until i unplug the cable leading to the tv for the computer. The question is really how can i change the dual screen display options without the cable being plugged into my computer as when its inserted i am not able to move the cursor or use any short cut keys??? please help. P.s i have run system restores which have not worked, i a have tried using old drivers for the display with no luck and also unistalled and re installed all drivers. I have run in safe mode, however it doesnt recognise dual screen when in safe mode so please help. thanks