Keynote fonts

I used a keynote theme for a presentation.

I was done with 50-60 slides.

I opened the presentation few days later for some changes

And BOOM

The font, that was used for a keynote theme not only updated

But also disappeared.

I tried looking in the Font Book

I don't think I have updated my laptop in the past few days

I have lost a very nice and important presentation (that I have to present in a couple of days)

Is there anyway I can get the font in the keynote theme or layout back?