Only in case nothing helps, then there is more powerful thing
docx repair
This blog might be too effective -
http://www.presentermedia.com/blog/2012/08/i-cant-open-a-powerpoint-presentation-in-2010/
You may read useful article:
http://www.pptfaq.com/FAQ00108_Recovering_a_corrupt_presentation.htm
Last one variant might be special solution for such desperate cases
The steps, which are mainly required for this solution, are shown below:
1. Open MS
PowerPoint program. Click on Office button (on top of the left side).
2. A window will be appearing. Now select corrupt PowerPoint file from the system directory.
3. Click on the arrow of Open button. A list will be scrolled down.
4. From the list, click on Open and Repair. After some seconds, the file will be repaired and opened.
Note: Though this solution efficiently works with corrupt files, but if it does not work we must try the following solutions.
1. We should try to open a corrupt file in OpenOffice.org Impress.
2. We should try to open a corrupt file in MS Word. If it gets opened, we can recover at least the text part of the presentation file.
3. We should try to import the slides from the damaged file into a new file.