Usually, the affected nail will fall off on its own within a few weeks because the pooled blood has separated it from its bed. A new fingernail will start to grow in around 8 weeks, but it'll take it no less than 6 months to fully grow. The regrowth process may take longer time in case there has been injury to the nail bed and/or surrounding tissues.
In a nutshell it's just a matter of time. Keep your feet clean and dry. And remember that the new nail may not look very normal.