CheckFileExsist

private void CheckExsist(ref string sourcePath, ref int counter)
{
    if (System.IO.File.Exists(sourcePath))
    {
        sourcePath = sourcePath.Replace(Path.GetFileName(sourcePath), Path.GetFileNameWithoutExtension(sourcePath) + "(" + counter + ")" + Path.GetExtension(sourcePath));
        counter += 1;
        CheckExsist(ref sourcePath, ref counter);
    }
}