Traffic,
Do they all play successfully? If so, you can just change the file extension on them.
In case you haven't set it up yet, click the View tab in Windows Explorer and make sure you're in the directory where the song is. Make sure 'File name extensions' is checked.
Replace .dat at the end with .m4a (audio container of MP4). If it plays successfully and it works, you can fix the other 995 songs with Bulk Rename Utility, and replace the file extensions at the end: https://www.bulkrenameutility.co.uk/Main_Intro.php
When the program is running, under Extension, select "Fixed" in the dropdown menu and enter: m4a
Then click Rename.
Let me know if you need any additional assistance in using that program, but other than that I wish you luck.
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.