Well it really depends, In general using ascii give you much better better chances of rescue (tough you shoul ennable incremental save NOW, as in pronto. Things like this happen a lot when you work for extended periods either because your tired or so).
So first things first, open the hypergraph, check if theres a intermediate shape somewhere. You wont see it in outliner. But the hypergraph will show if thats the case. Unmark them as intermediary. Alternate is to roll back your history nodes till it works. If you lost your history then your screwed.