|"....a blue box came up with writing inside(disappears after a few seconds).."|
That's a BSOD message.
Press F8 repeatedly while booting, don't hold down the key, and when the boot choices menu appears, choose
Disable automatic restart on system failure.
You will then probably get a blue screen message that will stay on the screen.
Tell us what the message says.
(we don't need the stuff in brackets after that)
Is a specific file name named ?
If so, tell us what it is.
You may need to use a Windows 7 DVD of the same version as on your system - e.g. Home Basic or Home Premium - to fix your problem, or the equivalent Recovery disk for your model , which you were supposed to make in Windows by using an emachines supplied program while Windows was working properly.
If you have neither, and can't borrow someone else's DVD, go to the emachines web site and see if you can get Recovery media for your model - if you can that's probably much cheaper including shipping that it would cost you to buy even an OEM Windows 7 DVD.
Or - you may be able to make a bootable CD or DVD of some sort on some other system, boot your computer with it, and replace or rename a corrupted file that is preventing Windows 7 from booting normally