Cannot logon to vista.

I have been trying to logon to a Vista computer which diplayed a blue screen and then froze.
Have tried to boot it in safe mode, without password and with password and still cannot logon since it says need reset password for all the user accounts on it.
If I try to reset the password and create a reset pswd diskette, still it does allow me to have access.
Please help what should I do to go past the stage and access my documents.