Sorry, bleach doesn't "wash" out. Bleach is bleach. At this point I would consider bleaching the pants in order to continue to wear them. Or on a long shot, try and dye the bleached spot to original color.
I agree with Naomie, once bleached, that's it. Depending on the size of the bleach spot, maybe you can dye the spot; or else dye the whole pair of pants a darker color.
Otherwise, you have a new pair of work pants.
You can't. Depending on where it is, sew an applicay over it.