Presentation opened only with two slides

I was creating a presentation during some hours yesterday evening. In the end of process computer freezed and it closed an application. I opened .pptx file again and I see only two slides, other dozens of slides disappeared. I've no idea how to work further, but in the end of the week I have to show this presentation on my job.

Other resolution can be to repair ms powerpoint pptx file via

https://www.pptxrepairtoolbox.com/

To resolve the above error message, follow the below mentioned steps:

1. Click File, then choose Save As.
2. Save the PowerPoint file at a new destination with the same or a new name.