im afraid not a lot but as there normaly hard to get rid of and they drop spores theres a realy realy good chance it will come back in its former glory . it mite be worth giving it an especialy good watering for a while .

most fungi like damp conditions and warm including athletes foot and thrush etc lol .

I'm not at all clear what it is that's died. Are you saying the whole lawn is dead, or that the fairy ring contains a strip of dead grass forming a circle, usually with toadstools either side of the dead area earlier in the year, and with grass growing in the centre of the circle?