Flight Attendant reported a nose landing gear issue resulted in an air turn back and precautionary landing at departure airport.

Narrative

After takeoff; before 10;000 feet; I began hearing a loud knocking and grinding noise every few seconds. I thought it was strange and wondered what it was. Shortly after; the flight deck called and asked if I heard it and where I suspected the sound was coming from. He said they thought it was a problem with the nose gear; that we were turning back to ZZZ and did not know if we would be able to get the landing gear down; so to prepare for that and that he would let us know. I called the back and told them to begin going over their commands; etc.; we made the necessary announcements. The Captain also gave an announcement. I chatted with the flight deck again; once or twice; about the sound; how I was doing; if the cabin was ready. I told him I was hoping for the best; but preparing for the worst. We heard the landing gear come down only it was louder; longer; and different than the normal sound. At this point; I assumed we would be in an emergency landing/evacuation situation. Then the flight deck called and said the panels all indicated there were no issues and that he was anticipating a normal landing. I relayed the info to the back; we did a quick cabin check for seat belts; and strapped in; still a bit uncertain what would happen. Just before touchdown; maybe 3 minutes to landing; the Captain called and asked if we were ready. I replied that we were ready. We landed safely and breathed a sigh of relief. We were taxiing slowly; we could see fire trucks (presumably to meet us if it went bad) and all of a sudden heard the computer giving the command 'remain seated.' We all began shouting our commands to remain seated. I was going over the next steps - release seat belts; how I would pull the large handle (not the small; that I am so used to pulling to disarm) and what the evacuation would look like. I reminded myself where the megaphone was and how; once every one was off; I would check the cabin. I decided in my mind who I would have help at the bottom as there was a family traveling in first with their 3 small children. So I decided the dad would not be a good ABA (Able Bodied Assistant) because he would want help his children.All this happened very fast. The passengers were unsettled and a little panicky from the commands being shouted. There was a lot of confusion. Then the phone rang and the flight deck said the alarm was going off; indicating an over the wing exit had been opened. Was it open; was someone trying to leave the plane? I did not know; said I would call him back. I ran down the aisle and arrived to see the exit panel off the window. I asked the passenger closest if she had taken that off. She said it had fallen. I ran back to the phone and let the flight deck know. I asked them if we would be going to the gate; which gate if so; or air stairs? Then I walked through the cabin telling people that everything was fine; there was a false alarm that the window exit was open; but all is OK and we would be at the gate shortly. The Captain then made an announcement and I went to my jump seat; then also made an announcement about taxiing; staying in their seat; keeping seat belts fastened; etc. we arrived safely; albeit very shaken up.