static void Main(string[] args)
{
string line;
using (StreamReader reader = new StreamReader(@"yourFilePath.txt"))
{
while ((line = reader.ReadLine()) != null)
{
using (StreamWriter writer = new StreamWriter(@"yourFilePath.csv", true))
{
writer.WriteLine(line.Replace(",",";"));
}
}
}
}
And if you want to write some headers just write a line before all this and for every new column you add a ";"