hosted site, upgrade has made dashboard minimal and uselss

I’ve been searching around on this issue as a user with a WP blog hosted by my website provider –
https://www.smileofthedecade.co.uk/newblog/
the dashboard I now have finally managed to get access to, appears to have shrunk to a useless miniature thing that I can only use to access my profile or the blog page – no more list of plug ins, edit post, add new, or much else of use.
I am an amateur at this and time has moved on since I thought I could manage such things – but being lost with no ability to write posts is frustrating to put it mildly. (Previously it logged me out every 4 weeks, which I could handle, but now I have to go to my cPanel to do that and am left with “Hi Pat” and the minimal useless dashboard…

My hosting organisation says this is a wordpress problem and I should seek help from “them” – so here I am.
I have tried to follow instruction on a thread I searched here, but I think its for wordpress site users – about getting into a current theme’s folder.
This is a problem as, if I go into file manager from my Cpanel and find the themes folder – it downloads what is a PHP file and of course I have no idea what to do with that..
My problem is also, trying to be a car driver without ever learning how to re-engineer the engine – and not knowing the language that well either.

But if there is something simple I can do to regain access to the writing and editing of my blog that doesn’t get me lost in php editing, I might be able to manage it…

(Brain is old and slow now)