I have one room in my home that is not blowing any air out of the duct. I checked to see if there was a damper and couldn't find one. The room directly next to this room work great but this room has nothing coming out of the vent. Not sure why this is happening.

Also my master bedroom has air blowing out of the vent but it seems hotter than the rest of the rooms. I was thinking that maybe this is because of only one vent in the room. Could adding another vent in the room make the room feel cooler. Was thinking that because the room is bigger it might need more than one vent to cool it off or heat it. Any and all help is appreciated.

Damper or blocked off completely, someone wanted to save money. Look again, way back as far as the duct goes where it branches off.
Warmer AC and cooler heat = furthest from furnace + uninsulated and maybe closer to the outside of the house (especially for heat). Also look for places where the ducts may have separated, or if the flexible kind, have holes.