1999 chevy silverado transmission auto 4x4?

Truck one day while driving wouldn't kick into 2nd, 3rd and reverse, so we took the transmission off and had someone replaced the gears, than the truck would not go into anything, no drive, reverse, nothing.. found out we didn't put enough fluid in it..once we did that we didn't have OD or 2nd so re replaced solenoid 2/3 and now OD kicks in, now about to change solenoid 1/2 to see if that helps because auto zones little computer said that was the problem, will that fix 2nd? and also its acting really funny do we need to try and flush the transmission?? the guy SAID he cleaned it after he rebuilt it but i guess not if we seen metal shavings in the fluid when we changed the solenoid..