Laptop second screen connection

Hello,

I have an Acer Aspire 5570 and the screen is completely broken lol. I used to connect it with my old computer screen and it was working, even if i unplugged the cable it would work when i plug it back. BUT since the last time ive unplugged it, it doesnt work anymore!! when the laptop starts, i can see ''windows vista'' bla bla on the second screen but as soon as i have to start my user session, the second screen goes black as if it was on stand by. How come it doesnt work anymore? Is it that my laptop is good for garbage or there's a solution?? The only one i found is to shut down the computer then open it again, so i can chose to wait 15 seconds for the restart, and there's 3 other options....ive choose to ''Restart In Safe Mode''. I can now see all my stuff, but theres no sound and theres some applications i cant do. Now im reading all the solutions on this forum but im too afraid to quit the safe mode and lose everything again so i want to be sure to have the good solution...should i press FN-F8?? PLEASE SOMEBODY HELP MEEEEEE thank you in advance