The stock market crash of 1979 took how long to recover to the level it was at just before the crashÉ

The Dow Jones Industrial index peaked at 897.61 on 5th October 1979 and fell every day thereafter (except two) to 808.36 on 24th October 1979. It bottomed out at 759.98 on 27th March 1980. It regained its previous high nine months later when it closed at 898.21 on 7th July 1980.

https://www.measuringworth.com/calculators/DJIA_SP_NASDAQ/

(on that webpage page enter Jan 1 1979 and Jan 1 1981 and it will list the DJI, daily, in the format mm/dd/yyyy index)