Missed my window to return lcwra form what do I do ?

So it's my own stupid fault. Advisor at the jc told me to apply for limited capability as I'm in a sling most of the time and gave very limited range of motion in my arms. That and a whole host is mental health issues either pre existing or from my epilepsy meds

I was very much under the impression they send me a form to complete and I'd return it. Cut forward to today and I missed my return date by 2 days having realised from a cryptic work journal note that I hadn't sent it back. It was in the post the same day as the deadline.

The work coach said to ring maximus but I'm not sure what to say to them. I really don't want to start this all over again because of my own stupidity and crappy brain fog epilepsy nonsense that's ruining my whole damn life