Read files from a Folder present in project

it depends where is your Data folder

To get the directory where the .exe file is:

AppDomain.CurrentDomain.BaseDirectory

To get the current directory:

Environment.CurrentDirectory

Then you can concatenate your directory path (@"\Data\Names.txt")

below code should work:

string path = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), @"Data\Names.txt");
string[] files = File.ReadAllLines(path);