Were helicopters used in World War 2?

Yes.

• Kellet KD-1A (La Cierva C.30A) (General Use Autogyro)
• Sikorsky VS-300 (Experimental helicopter)
• Sikorsky R-4B "Hoverfly" (General Applications helicopter)
• Sikorsky YR-4B "Hoverfly" (Ambulance/Sea Patrol helicopter)
• Sikorsky R-5A (Rescue/Reconnaissance helicopter)
• Platt-LePage XR-1 (Experimental helicopter)
• Germany's Focke Archelis Fa233 4 seat/cargo helicopter
• German Kolibri single seat coaxial rotor

The German FA 233 was used extensively in 1945 including the resupply of Breslau. Approximately eight were in use in 1945.

The Sikorsky R-4 and R-5 models were used for costal patrol and search for the continental USA in 1945, and a a few were deployed aboard ship to be used in the Philippines, but none of those were actually employed there. Total production of operational helicopters by the USA in WW2 was under three dozen.

From a practical standpoint, however, helicopters were too new and immature of a technology, and only a few were built and utilized in small numbers. They had no measurable effect in WW2. Helicopters would come into mass use (and demonstrate a significant contribution) during the Korean War a few years later.
The first helicopter in warfare was first used in Korea was the Sikorsky HO3S-1 which was used primarily for transporting the injured to the M.A.S.H.