You don't have any backup copies of your thesis?
ARE YOU NUTS! (yes I'm shouting at my screen) You are just begging to fail or have a heart attack!
You should be making frequent backups as you edit. At the very least daily (ie start each new day on a new copy of the file so that you can fall back to known good copies that are not missing too much content!
This problem you had is just a trivial example of the problems you could have. If you have equations and images in your document it could crash at any time with a known fault.
Here are some macros that can help you:
1 True Autosave Macros for Office
Unfortunately, although Office apps have been around since the the mid 1980’s, MS has not figured out that we need a good “Autosave” backup feature. In the past there was a “versions” feature in some office
apps, but it only kept incremental copies of files, not ful files. Windows 7 has a file “versions” feature, but it is tied into “System Recovery Points”. Not very useful.
The following links tell how to setup macros that run automatically and use SAVEAS to save full copies of the file with the date/time included in the file name. You have to manually delete the “extra” backup files, but you control the process rather
than Windows or Office. It is a bit more work, but I find it worth it for very important files that are changing frequently.
Automatically backup Word documents http://www.gmayor.com/automatically_backup.htm
Graham has created an addin that does something MS should have done 20+ years ago.
<snip>
Contrary to popular opinion, Word has no integral means of automatically saving the current document, nor of backing-up the current document. What it does have is an option to save
AutoRecover information after a specific and configurable interval and an option to save a backup copy of the
previously saved version of the document with the default file extension of
WBK (and although there is no reason to do so, Word also allows the option to change this extension to the user's choice). This is not a true backup in as much as it is not a copy of the
current version of the document.
A function to create a true automatic backup is provided by the
**Save In Two Places add-in which is detailed in a separate page**, There is also available from this web site a complementary add-in which provides numbered versions
of a document. **Again that has its own web page.**
</snip>
Save Numbered Versions Add-In for Word 2007 & 2010 - http://www.gmayor.com/SaveVersionsAdd-In.htm****
Save the current document in two locations add-in for Word 2007 & 2010 -http://www.gmayor.com/SaveInTwoPlacesAddIn.htm****
Performs a normal save in one location, then does a DOS copy to the second location (ie USB)
Making Backups as You Work - http://www.informit.com/articles/article.aspx?p=731710&seqNum=5