A corporate jet First Officer reported that the landing gear did not retract and a return to departure airport.

Narrative

Upon takeoff on Runway XX gear retraction was commanded by the PIC. Gear lever was placed in up position. Gear did not retract and a CAS (Crew Alerting System) message of 'Landing Gear Not Up' Received. PIC was advised and requested straight out climb from tower controller. Vectors were requested while the appropriate checklist was conducted. Speed was maintained under 200KIAS while climbing to 3000 feet. We were switched to departure and we requested vectors again to run checklist. Checklist was run and gear lever was selected down in accordance with checklist. Checklist commanded to leave the gear in the down position and land as soon as possible. We requested a landing to the departing runway after running landing configuration and performance data. Gear was confirmed in the down and locked position according to position indications and gear was never retracted. Landing was normal and without incident. It was determined that one of two gear position switches on nose gear had reported to the aircraft that it was still in the on-ground position and the discrepancy resulted in the gear not retracting. Switch was repaired by company maintenance personnel and tested. Subsequent flight showed normal gear retraction and continued without incident.