Do you have any lights etc when pressing trigger? Mine would do everything right with lights etc, however when trigger pressed it would hardly ever do anything.. found the problem was with the speed selector switch on top. When in pulled drill apart i found the selector switch makes contact with 2 metal tracks, these were really dirty.. after cleaning them it works perfect.. just be very careful pulling apart as there are a few small pieces that can come loose.
This was on a ryobi 18v