I am sorry to have to tell you that the file is full of zeros - there is no information in it and all your information is lost.
Can you remember what happened to cause the problem? In particular
1 were you editing a .doc or a .odt file?
2 had you saved the file before? Or had you created a new document, added a lot of content, and then this happened?
3 Do you have Tools > Options > Load/save set to AutoSave?
4 Do you have Tools > Options > Load/save set to save a backup copy?
5 Was you file stored on a USB memory stick? A RAM disk?
6 Did you close Writer, then start Writer again very quickly?
7 Did you save the file, and then close Writer very quickly?
My
guess is that Writer had reserved space for the file, but crashed or the PC crashed before the contents were written to the file. It would be good to know so we could warn people what causes this problem.
How to minimise the effect of its happening it in future.
1 Always take a backup of changed files every day.
2 Always set AutoRecovery to save a copy of the file while you are working on it - it protects against things like power cuts, OS freezes etc. Tools > Options > Load/Save > General
3 Always set Create a backup copy to ON - this keeps the previously saved version of the file. Tools > Options > Load/Save > General
4 Do not be over quick to power down or hibernate your computer
5 Be very careful if you save to a USB stick - be sure to Eject it safely.
Why? In order speed up PC when talking to slow things like memory sticks, Windows writes the data to a high speed buffer, and then copies the data slow-time to the USB stick. If you pull it out before the buffer has been written, you lose that data. See
Safely remove devices from your computer for more information. I think Windows 7 can be set up so as to not to use the write buffer, and always write direct to the USB stick, but I forget how.