What was found
CREW REPORTED ON TAKEOFF THE LG WOULDN'T RETRACT AND LG DISAGREE MSG APPEARED, CREW DECLARED AN EMERGENCY AND RETURNED TO FIELD AT PIT. THE A/C LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT, AND REMOVED AND REPLACED NLG PROX SENSOR PER EMB AMM AND PERFORMED GEAR SWINGS, OPS CHECK GOOD.