Premier Pro producing a 4 hour video that's corrupted
The first place I would look would be in the encoder log files. If you used Adobe Media Encoder you will find the log files here:

Windows 7 &amp; 8:

C:\Users\[user]\Documents\Adobe\Adobe Media Encoder\8.0\AMEEncodingLog.txt


Mac OS:

/Users/[user]/Documents/Adobe/Adobe Media Encoder/8.0/AMEEncodingLog.txt


To view the log file, choose File > Show Log or press CTRL + L.

There are two log files:


AMEEncodingLog.txt - for successfully encoded jobs
AMEEncodingErrorLog.txt - for jobs that failed, or were stopped by the user


See the help: https://helpx.adobe.com/media-encoder/using/log-files.html

Check the last entry in each log file and see if your video was encoded correctly.


If the log file points to an encoding error, investigate that
If the log file indicates no error then attempt to play the video in a different media player and see if the problem still persists  


I use VLC media player because I've found it to be most reliable.  There is also a debugging console in VLC that can be useful.