A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
I'm not sure why you believe there must be a way to rescue a corrupt file. If you have a deadline, you should get started on a replacement.
You can try making a copy to another folder. Add .zip to the file ending, then unzip the file. Look in the ppt/media folder for pictures and music you had placed in your file. Using a text editor like NotePad++, you can open each XML file in the ppt/slides folder and extract text, though it's a pokey process if you had applied lots of formatting to your text.
Here's my article about repairing documents. While this was written for Word, the techniques are similar for PowerPoint. There may be some tips that will help you salvage as much content as possible: OOXML Hacking: Document Repair