I'm working on the code for the project. I worked pretty well, but now it has suddenly become impossible to call functions. It says: "not declared in this scope" for everything? I can't figure out what causes this issue. It is giving me this exact same problem in other sketches that used to work before too.
This is impossible to diagnose without the code. Is it Arduino? Java? You can send me the project, so I can have a look.
Usually this kind of problems originate from minor mistakes, like a { or } missing or at the wrong spot... try formatting the code, sometimes you see this kind of small errors easier that way.