I am a total beginner to C# and OOP, I created a project...

As the title says, I am a complete beginner to C#, i created this project for an internship, but i am unable to seem to run it again? I have no clue what problem it is as it was running fine yesterday night. I think there might be a problem with the file locations or something similar but if someone would be so kind to send me a DM so i can give you more details. Any help is appreciated thanks!:)