What can i do if my toe nail has come off, should i be worried?

Usually not: It happens. As long as it is not infected ( red, swollen, painful, draining) try this: gently cut off any nail that is free ( not attached) and clean or soak in warm soapy water. Dry, apply an antibiotic ointment and cover with a bandaid while wearing shoes. Expose to air when you can ( over night). Ifi it either begins to grow back discolored or thick, or if it becomes painful then seek help.