Dell Laptop turns black with cursor only after Window startup

Hello,

My laptop turns black with the cursor only shown right after Window startup. The problem occurs when I first start the laptop then my AVG anti-virus detected some threats right when the desktop displayed. As usual, I performed the recommended action to remove the threats, then my laptop is requesting for a Restart. When my laptop restarted, the screen now turns to black right after the Windows startup with only the cursor shown. I suspected the file threat I recently removed has something to do with the missing piece during startup.
Then I search how to repair the problem. I tried F2 to Load Setting Default, nothing happens. I also tried F12 to check with the Diagnostic option, still nothing happened. I also tried Hard Ware option under F12, but nothing happens. Now I checked with F8 to see if there I can use the Last Good Configuration, but then the black screen still appears. I tried opening in Safe Mood but after few scan the laptop freezes and black screen came out with cursor only. I'm looking for the option "Repair Your Computer" under F8 but nothing is shown.
I hate to admit it since I have all my important files in drive D and some very important work related software installed in drive C. And now my guess is that my last resort would be to restore it in factory setting. The problem is I don't have the CD/DVD for the installation guide or whatsoever.
So I humbly ask for help from any experts out there who could possibly help me, at least salvage first my laptop files, if not before I go with restoring to factory setting.