Then I'm sorry to say, I don't think there is much of an alternative than perhaps to take it back to the store for them to deal with, if it has been purchased really recently (within the store's return/exchange period.)
A: Another Expert here may have more ideas as to what to do with this case (and I will give you a chance to hear from another Expert soon, most likely.)
B: Can you try to boot up in Safe Mode for me? It probably won't work, but if it does, you will be able to get into your system I think.
To try to boot up into Safe Mode:
- from a powered-Off state, turn the computer On, and immediately press the F8 key, once or twice a second, until the text-only Safe Mode selection screen appears, with a highlight bar across it.
- then using up and down arrow keys, move the highlight bar to Safe Mode, and press the RETURN (or, ENTER) key, once.
- the computer will boot up in Safe Mode, a reduced mode of Windows with a less-detailed or colorless screen, into which you may log in, and do whatever operation you need.