I think forum is replacing text smileys with something non-existent. Can I replace those in Admin CP, with some other images?

I deleted two ancient custom emoji tables I had, is it possible these were from there?

ou should never delete tables from your site, under any circumstances. You would need replace those images in the folder if they are no longer present

Nope sorry for my wording. Not tables. In Admin CP I deleted custom emoji something...

They were ancient emoji packs and many where inserted as markdown into the text.

Yes, if you have deleted them and they no longer exist on disk, they could well cause the above. What you could do is replace just the files within the location its looking for them