"........and used F8 to get to the list of commands. I have then tried almost all the commands available including 'Boot with last good configuration' and 'Safe modes' with no success."
Do you get the option for "Repair your computer" which is usually at the top of the list? If you do then select it, follow the prompts until you reach this screen then select "System Restore". Choose an available restore date when everything was working fine.