[MOVED] Can't access Zorin desktop screen

I updated my computer and restarted to apply. When the computer restarted I received a blue screen with LINUX in approx 1.5 in letters in the middle of the screen on the left side of the screen it had Bit Defender with a box to enter the password. I have no clue what the password is and can't remember ever installing Bit Defender. Anyone have a clue how to use a back door into Zorin? I have a local friend that has more expertise than myself and is unable to resolve. I have two partitions one is Zorin the other Ubuntu. I've read about using Ubuntu as a Swift Army Knife to deal with this type of problem, however, so far no luck. Thanks

OK, what version of Zorin is this and what 'updates' had you applied? [PLEASE NOTE: The how-tos and tutorial sections are for guides not questions on problems - ALWAYS use the Help and Support section. Thanks.