windows not working?

When I turned on my computer,it said that windows didnt shut down due to new software or hardware that had been installed and to choose one of the options to restart-safe mode,,last time used or will start after 20 seconds.Have tried all 3 (may be a 4th one cant remember).Windows page comes up with searching bar then goes back to options.
The only items I have installed are Microsoft office and my printer.I used it yesterday with no problems.
Any help wouldbe greatly welcome as Im not very computer minded
Thanks

RB
December 2011