Hello april
Try this:
As soon as you turn on your computer start tapping the f8 key. Keep tapping it until a black screen pops up with loads of writing on it. This is called the boot screen.
Use the arrow keys and move to the option: 'Last Known Good Configuration'. Press Enter. If that doesn't work, restart and go back to Safe Mode. This time try selecting Safe Mode.
Once there do a full system virus scan. Hopefully you will then be fine.
Let us know how you get on