When you start your computer, just spam F8 until a menu pops up. It will have the option "Run Safe mode with networking" in it. Use your arrowkeys to scroll up to it and enter to use it. Some weird shit will happen and there you're in safe mode.
what subject ? Keep trying and don't give up ;)
About the safe mode and that shit, in windows 7 the administrator account is hidden and you can activate it (doesn't require pw to log in on the session) , but you maybe need to run the console as admin, I didn't try it tbh. Search on google about this stuff and maybe you will find something useful