I travelled to a wedding once, left my car at the reception but stayed with family nearby. The next morning I ran to pick up the car. A passing car threw up a stone that hit me in the eye; it hurt, and I couldn't keep it open to see out of. A passing car say me struggling to stay upright and stopped to help. They were an off duty nurse and police lady - and they decided I needed to go to A&E.
I didn't know my wife's mobile number, and couldn't remember my bro-in-law's address. The only numbers I could remember by heart were my mum and older brother - both went to voicemail.
In the end I had to describe how I would drive to my B-i-L's while they looked at Google Earth so that they could suss out where his house was (I couldn't see, sou I couldn't point it out to them). They then drove round to let my wife know I was in the hospital and would need picking up.
After that I started wearing an ID bracelet, although I have fallen out of the habit. I guess I should start again.
It was the Vital ID bracelet -
http://www.theidbandco.com/Sports-Safety-ID-Wristbands
You write your details on a waterproof slip that fits inside. It means if I am overseas work I can put the insurance/ hotel details on it.