I can't access my HP Windows 7 laptop because it is locked

I can't access my HP Windows 7 laptop because it is locked. Before, my laptop had no password so i can easily access it but I have put a password in it, after i restart, a new User name KIOSK appear, and there is another option, so i chose Switch user then there is Other user, but when I input my Username and password, it doesnt accept it, ive tried so many user name like, guest, administrator, but still it will always say, the user name or password is incorrect. I then restart and press f11 for system repair but the screen says that the windows failed to ]. a recent hardware or software change might be the cause. info, the boot selection failed because a required device is inaccessible. Can anybody help me on how can I access my computer again without this problems? Im so worried now. I have so many files in it.