Clunk and now won’t start

have you been hearing any knocking noises prior to this event?
How many miles ,
how frequent are the oil changes?
Does it crank? and not start
does it just have the lights come and not crank?

What year and engine? Was it still running (the engine) when you coasted to the side of the road? Did you put it back in park after coasting to a stop? Does it roll while being in park? The only thing easy I can think of is that is easy if the engine was still running is a CV axle or driveshaft CV failed. That wouldn't prevent the engine from starting though, unless the shifter wasn't in P or N though.

Thanks all, no clunking prior and no history of issues and regularly serviced. 89,000 miles on the clock and it's the V6 diesel. It felt initially like I'd just run over something and only when I went to accelerate after realising it wasn't that did I see the car had lost it's accelerator function do I coast to the side of the road. The 4x4 selector flashed on the screen and seemed to act like it was in 4x4 mode. I thought to try and turn off and on again and then it wouldn't re-start. When I press the brake pedal its stiff and doesn't budge and it just then clicks and restarts the computer/ignition screens and goes blank. Roadside recovered and the garage it got towed to said it sounds like a crankshaft failure and needs a new engine to the tune of £10k+..... Resale value is only £20k so at a loss what to do tbh. They haven't confirmed that yet as they are bust until next week but they're a LandRover specialist so not exactly new to the issues I guess.