Unregistered car notice on a registered car

TL;DR ute is registered, no engine, been at my house around a month, what's the play? I'm I screwed or can I fight the notice given its registered and I've been actively working on it?

Hey so I just got home after work to find my ute I've been trying to fix has been slapped with a yellow sticker, despite being registered, someone stole this ute from me mid last year and after I got it back, I found out the people who stole it blew up the motor, I had it at a mates place until I found a parts bin car to donate its engine to my ute, I've had it at my house for about a month now, and I've been working on replacing the motor, I pulled it and now I'm just trying to freshen up the new one, do all the stuff that's easy to do while the motors out yk, I'm so close to getting the new motor in and this shit happens, is there anything I can do? Or do I just have to move it onto my front lawn or something? I have a winch on my other ute, so I can get it up there (where the tub of my other ute is) but it's gonna be a massive PITA to try and install an engine on a steep grassy hill, am I just shit outa luck?