Google Analytics by default cannot track any file downloads by using standard GATC implementations, since a file download will not trigger a new pageview. Thus, you will need to create a virtual pageview to trick the system to generate a pseudo pageview when someone downloads a file from your website.
For example, if your original link looks like:
You need to modify the above link to look like:
By doing so, you will generate a virtual pageview when someone clicks on the download link. Virtual pageviews are captured in the Top Content and Content Drill Down reports.