Can not open some of the files. 

What is the extension of file that you are trying to open in word 2013. Also what error message did you receive while trying to open those files.

You can try the below mentioned steps in order to open file. [see if it helps]

Step 1: open word document

Step 2: click File>>Options>>Trust Center>>Trust Center Settings>>Protected View

Step 3: Under Protected View, uncheck all the three options [see screenshot attached]

Step 4: click ok and retry opening the files.

You have to be more specific. What happens when you try to open the files? What are the symptoms?

Have you tried repairing the files?

Note that turning off Protected view in general isn't a good idea. To open older files, you may have to change the File Block settings for older file types (look in the File Block Settings category of the Trust Center dialog box), which is different from disabling the options yo