On windows you can get at its create timestamp with
http://mindprod.com/products1.html#FILETIMES

You can see if it exists with File.exists

       // set up handle to file name.
       File f = new File( "E:\\genus\\species\\crocodile.html" );

       // does the file exist
       if ( f.exists() )
           {
           System.out.println( "file exists" );
           }

Then your program logic if faulty. What prevents you to first trying
to delete any previously existing file? What prevents you from not
doing the processing if your file creation fails? Did you try to be
clever and are you ignoring exceptions?

This is basically an unsolvable problem.  The best you can do is sort of
fake it.  Put enough wolf-fencing around the file and hopefully you will
never get to the point where the entire system fails because all of the
different checks go awry.

This is a transaction system similar to what many databases use.
There's several ways to solve this, I'm sure.  One would be to log all
transactions (files) and to have the other side also log all
transactions.  That way, if (and when) the system fails, you can
re-start and read the logs to determine where you left off.

You may also need to create some sort of ticket or cookie.  For example,
if two sides are communicating, you may want to create a ticket that
says "Processing-file-MyFile.txt-28/SEP/2007.18:34:23.42112-Line-1" then
process that line, then log "Completed-file-...etc..-Line-1" then log
"Processing-file-etc...-Line-2" and continue on that way until the whole
file is processed.

(Of course, recording lines processed may not be important.  Just choose
whatever sub-unit is appropriate.  If the files are simple and quick to
process, you could do them in one go.)

Then on the other end, record the ticket given, and when and if the
processing was completed.  Then when the system fails, it can be
restarted and the first bit will ask the second bit whether any parts
haven't got to the "completed" part yet, and if there are, restart from
there.