Usually, there are two way you can try to recover your former power point files.
First one, check the AutoSave. For our computer, when files such as Powerpoint and Word corrupt, it will AutoSave the files. Although not the all of the file. The premise of AutoSave is have set the AutoSave interval. The path to check the AutoSave is:
1. Go to folder
2. Choose Go, then go to folder
3. Enter “/Users/”
4. Choose your user name and enter
You will find the path “/Library/Application Support/Microsoft/Office/Office 2011 AutoRecovery”

Different version of office, the path may be different, for the office 2016, the path is /Library/Containers/com.microsoft.Word/Data/Library/Preferences/AutoRecovery/

Second, try to use the data recover tool to recover the lost or deleted files, such as documents, images, videos etc.

Three ways:
1. Recovery with iTune if back up.
2. Recovery with iPhone recovery tool.
3. Ask for the help of professional service.

I think it will very difficult to recover, because you have install the window 10. The space where store the information about window 7 have occupied. But recently, I have read an article about how to recover deleted files on Windows and Mac, you can have a try.

For recover lost data in iPhone, you can need to try some iPhone tool. There is an article about top 3 iPhone Data Recovery for Mac tools ,
you can have a try.