The most common causes of the big toe nail coming off the nail bed is due to a traumatic injury, light rubbing of the toenail within your shoe that you never even noticed, a very severe fungal infection or in some cases we may never know the reason it fell off.
First confirm that you have actually experienced trauma, this is usually pretty evident because you stubbed your toe really hard or dropped something really heavy onto your toe.
You will experience the following symptoms:
Most likely to get it:
The nails would have been thick, hard and discolored yellow or orange for a period of time before the nail separated. This is a very common and treatable cause of nail separation.
The priority in this situation is to accept that the nail has been lost and that you will need to wait until you can grow out a new nail.
Other Related Nail Problems:
What is onycholysis?
See if any of these other problems apply to your situation!