No, that is a complete myth.
I think you are being facetious. . . ;^)
But if you're not. . . Then your theory is? FDR ended the depression? The tooth fairy? Aliens??? The industrial infrastructure in the USA was destroyed by? What? Every trained machinist forgot what he/she learned making weapons? The growth in technological knowledge was thrown away because it wasn't needed for the war effort?
Add the economic stimulus of postwar rebuilding Europe and Asia. Investment, raw materials, and JOBS had to be produced over the next two decades to repair the damage. That put the world on the western side of the Iron Curtain to work. . .
.