Sony Vaio VPCEE3E0E password help please

Hi All,

I got a my laptop at Christmas and set a password to be inputted when the computer opens up (before you get to Windows). This password has worked absolutely fine up until this mornng when it wouldn't work and I'm getting the message: "The user name or password is incorrect"
I'm the only user so I'm sure that's correct and I know that I'm definately using the correct password as it's the one I use for everything.
Please can anyone help me with this? Any help is very much appreciated.
Thanks
Lindsay