A file that ends in a DAT extension contains information for a specific program or document on a computer. These files join so many others that it can be difficult to know what to do with them. For example, a DAT file in a Microsoft Excel document can not be opened with Microsoft Word. To discover how to open it, you have to do a detective job to find out what program it is associated with.
Open in Word
Open Microsoft Word. Wait for the program to load completely.
Click on "File" and select "Open." When the dialog box opens, find the DAT file you are looking for, click on it and press "OK".
Examine the file. If it is DAT of a Word document, it is easy to read the data for that particular document to which it is associated. If it looks like a mass of strange characters, it is associated with another program and you must open it using other methods.
Open using a rich text program
Open a text editor such as Notepad or TextEdit. Click on "File" in the menu bar and select "Open" and choose the DAT file you wish to open.
Look at the DAT file. While it will often be a mixture of strange characters, sometimes you can recognize certain elements. For example, you could recognize the names of the categories of an Excel document that was created months ago. This means that the file is from Excel. If you still can not recognize the file, you will need to use another method to identify it.
Open the document that corresponds to the DAT file. Check that it is correct and select "File" from the menu bar. Choose "Save As" or "Export" and find the option that allows you to save it as text (TXT) or in rich text format (RTF).
Start Microsoft Word. Click on "Open" and look for the TXT or RTF file that you just saved. Select it and press "Open".
The method of guessing
Find the DAT file you want to open. Click on the right button and on it and select "Open As". This will open a list of files.
Open the DAT file with each of the programs in the "Open With" menu. It is a tedious process, but when you have found the correct program, the DAT file will be displayed properly.
Save the file as TXT or RTF within the program with which it is associated. For example, if it turns out that the DAT file is a PowerPoint, click on "File" in PowerPoint and choose "Save As."
Open Microsoft Word. Click on "Open" and find the RTF or TXT file that you saved from the DAT file. Click on it and press the "Open" button.