While waiting for my shuttle to the Geneva airport, I realized I did not receive a check-in email or text message 24 hours prior to my flight. A woman on my shuttle was also on the same flight. I asked her if she received the email and she said she received an email and text message. This worried me because I did get an email for the arrival flight from Phoenix to Geneva. I arrived at the airport two hours early for my flight. Walked to the counter at the same time as the woman from my shuttle. She checked in with no issues and told me she would see me at the gate. When I told the young man my name he was not able to find it anywhere on the flight. I then showed him my email confirmation I received from United Airlines. He acknowledged that I was showing him a valid confirmation but said again he could not find me. I asked if there were open seats and he said yes. When I asked if he could assign one to me he told me he could not and that his manager would have to do that. At the time the manager was working with another passenger. While we waited he assured me that if I could not get on that flight there were other flights that day he could put me on. And also that he could even walk me up to the gate if need be and they could get me on the flight. His manager came over and he explained the situation. She immediately replied there is nothing I can do for you the United States has to book you on this flight and they are not answering the phone. The manager got on the phone while saying something to the young man afterward. It was not in English so I didn’t know what it was. The young man then told me to step over to the next counter and his co-worker would take care of me. After that he left his counter and I never saw him again. I then had to re-explain everything to another employee. At this point a lot of time had passed, but I would still have been able to make the flight. She told me she didn't understand the problem because her co-worker had not said anything to her and asked me if I was late. I told her no, I was not late I arrived two hours early. She was not able to find my name anywhere on the flight. She then told me she could not help me and I would have to fly out the following day at 10:45am. I told her that was impossible and that I had to work at 6am the next morning. I asked her if she could book me with a different airline then and she immediately said that everything else was full. I asked her to check and she said we only share code with Swiss and they are full. Even thought I never saw her check anything on her computer. I said it shouldn't matter who they share code with considering I had paid for a flight and was being denied access to it even though there were seats available because they had somehow deleted my booking from their system. She then pointed to my bag I was going to check and asked me if it was mine and if it had any liquids in it. I told her yes I have liquids in it. She told me I would have to throw them away. I asked her why and she said because if I were to go through security with it I couldn't have any liquids in it. I told her that doesn't make sense that I should have to throw away my expensive liquids in my checked bag when people are allowed to bring liquids through TSA. Then I got out my luggage key and started to get my liquids together. She looked down at me and told me that it was too late. Then she got on the phone with someone and stopped and said to me "Did you or did you not refuse to throw your liquids away". At this point I could not believe all of this was even happening to me and was not about to argue with her as I was now stranded in Switzerland with no return flight to Phoenix and I still needed to be at work at 6am the next morning. I told her I did not want to but I would have. After that she said she could get me on a flight out later that day with Swiss Airlines returning home at 11pm that evening. I wasn't happy about arriving so late since I had bought my original flight so that I could be home at a reasonable time to get to work in the morning but I took it. I asked if it would be possible to be put in Business class for everything that I had been put through and if it was still possible to get a vegan meal as my original flight I had requested one. She printed me out something and had me go to the Swiss counter to check in and ask about my requests. I then walked over two desks to the Swiss counter and asked the girl about the meal and upgrade. She told me I would need to go over to the Swiss office and ask them and come back. I went to the Swiss office and the woman told me that it was too short notice for a vegan meal and that the flight was full. Then I went back to the girl at the United counter almost in tears at this point and told her that the woman at the Swiss office told me the flight was full. She said something to the girl two desks over at Swiss Airlines, (the one who had told me to go to the Swiss office) and told me to come back to her counter. At that point she got a very bad attitude with me and told me that she already told me that I was on that flight and that if I wanted anything special after that I would need to check with the Swiss office and after that I needed to come back she would check me in and take my bag. All of this was said to me in a terrible tone and borderline yelling at me. None of this should ever have happened. It makes zero sense how I could purchase a flight and have no problems checking in on the arrival but my return trip is somehow non-existent in the computer. After the way I was treated and everything that I was put through I feel I should be entitled to a refund for my flight.