Lift your circle saw's blade guard up and remove the screws holding it in place with your screwdriver.
Use a socket set to remove the blade's retaining bolt, and remove the blade.
Place the blade inside your workbench vise and tighten the vise. Use pliers to bend the blade slightly into shape.
Remove the blade from the vise, and lay it flat on the work bench.
Tap around the edges of the blade working inward in concentric circles with your rubber mallet. There is no need to pound the blade. A gentle but forceful tapping motion is all that is needed.
Install your blade back on the saw after the blade is straightened.