Cannot remove italic from font text style

Things were working just fine until today Figma randomly decided to make my Body text style into italic, although it is 16pt Larsseit and Regular.

Somehow the font file has switched and when I deactivate the italic (CMD+I) it changes the font back, but then looses the link to the text style, and so I’m stuck.

My question is: how do I go about re-installing a font, or re-linking the correct font files?

I’m working on Figma desktop, on a Mac, and have installed the Figma font agent.

Not sure how to delete my original question, so I’ll post my solution: re-install the font from the computer font manager!