While trying to set a constant altitude in the LEGS page before a step climb in the FMC, the plane shut off LNAV, and went to MCP controlled mode. When I removed all of these altitudes, the speed and altitude lines on the LEGS page remained blank, and the VNAV page had MCP active across the top, and no VNAV information anywhere. Is there a way to get the VNAV info to return in mid-flight right here, or did I basically screw up and have to control it by hand the rest of the way when that happens?

Did you try reloading the flight plan, then clearing all waypoints already passed?

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