I can see your Home page currently does not have much content, but it is not possible for me to see what happened to it. The most likely thing would be that it was accidentally deleted while you were editing something else. Unfortunately, this content would need to be rebuilt.
I can see that you are on an older builder. You can add an image of an Instagram icon and link that image to your page, but if you want a builder that has more social media capabilities, I would recommend rebuilding your site in our newer builder, Website Builder. This newer builder also has a "save history" option, to prevent issues like this. You would be able to re-load a previous version of your site instead of needing to rebuild. I highly recommend you look into using this newer builder.