IFO files are nothing but DVD video file formats so you can play IFO files using any DVD player. The most common DVD players include VLC player for Windows and VLC player for Mac. Moreover, you can also play these IFO files using Windows Media Player on Windows. There are also many external media players which have support for IFO video files as below
You can use any of the following software to open an IFO file on Windows:
CyberLink PowerDVD 10.
Nero ShowTime.
WinDVD.
Roxio Creator 2010.
On Mac, you can use any of the following applications to open an IFO file:
Roxio Toast 10 Titanium.
Wired WiredStream.
Apple DVD Player.