Please help me! A very important document that I spent many hours working on has somehow gotten messed up.

My computer restarted for no reason, and when I logged back into Windows the first thing I did was open my document.
When I opened OpenOffice, it asked me for my first and last name and initials. Now whenever I try to open my document, a menu is brought up saying ASCII Filter Options. It asks for Character Set, Default Font, and Language. No matter what I pick my document will only open in read-only, and all of my text has been replaced by a huge wall of ################ symbols! How do I get back everything I wrote?
Please help if anyone knows what happened and how to fix this! I would appreciate it so much.
Thanks
Lauren