I'd like to learn more about properly resetting the zero on the turrets, using the zero stop and precisely using my elevation/windage turrets for setting up a DOPE card for shooting my 22LR rifle at various ranges. Is there a manual or video? Scope: EP-4 6-24x50 MIL FFP

I lost one of the 4 screws for my top turret while trying to reset zero... how can I source a replacement? Scope is an EP-4 MIL FFP 6-24x50