The bigger question is, why did it happen… To answer that, you need to make them level again. Turn off the printer and unplug the Z motors from the wiring harness. Turn the RH motor shaft until the X axis is visually parallel with the aluminum bed plate. Use a scale to measure from the AL bed plate to the lower X smooth rod. Adjust the X axis position by turning the Z axis motor shafts until the measurement between the AL bed plate and the lower X smooth rod are equal on the right and left sides of the bed.
Reconnect the motors and turn the printer on. Using the printer controller in Cura, move Z up or down a few mm at a time. Are both Z motors turning?