Is it your own website or someone elses?
I haven't properly tested but I wrote a script for you which seems to work fine.
I can't paste code to help you as the php quotes don't work.
I have put the code here for you though pastebin D()T C()M/967yxyQx
You need to place all your text files in the same folder, edit the top of the script with your user details on your blog and run it. It will post all the text files to your blog in the category you entered.
You will need a file called IXR_Library()php()inc which I also can't attach but you can google for it and put it in the same directory.
I have a way that will post text files in to a category of choice. From the admin area click and go, you will need to upload all txt files for the post through ftp.
The txt files need to be set up correctly, it is not difficult to do. I use it frequently, loads 100 posts to one category at a time. I will need time to get it together.
Are you interested?
Also, if you like I could alter my script to loop just a single file?
Let me know, do you have a small example file so I could see it?