My 2012 theme is showing the incorrect font

Please could somebody have a look at my site which has changed from the default theme font to a different one that I don’t want: https://www.newrobotclub.co.uk

I am fairly new to WordPress and trying to learn, but I guess I have poked around where I shouldn’t, and now can’t put it back to how it should be.

I have tried deleting the 2012 theme and reloading it, but the problem is not solved.

I’d be very grateful for any suggestions before I pull the rest of my hair out.

Thanks very much. David