Load data from specific lines in a text file into SQL using C#

How big is the file? If you can read it all into memory, it'll make life a lot simpler:

string[] lines = File.ReadAllLines("file.txt");

// Could use lines[lines.Length - 1] but LINQ makes it simpler...
string lastLine = lines.Last();

IEnumerable<string> otherLines = lines.Skip(1).Take(lines.Length - 2);

So that's the "getting the data out of a file" part. For the database part, you haven't really given us enough information to help you. You need to determine how you're going to do database access (straight ADO.NET, LINQ etc) and then read tutorials on that topic. There are plenty around.

Try this found it online for you

public static String ReadLastLine(string path)
{
    return ReadLastLine(path, Encoding.ASCII, "\n");
}

public static String ReadLastLine(string path, Encoding encoding, string newline)
{
    int charsize = encoding.GetByteCount("\n");
    byte[] buffer = encoding.GetBytes(newline);
    using (FileStream stream = new FileStream(path, FileMode.Open))
    {
        long endpos = stream.Length / charsize;
        for (long pos = charsize; pos < endpos; pos += charsize)
        {
            stream.Seek(-pos, SeekOrigin.End);
            stream.Read(buffer, 0, buffer.Length);
            if (encoding.GetString(buffer) == newline)
            {
                buffer = new byte[stream.Length - stream.Position];
                stream.Read(buffer, 0, buffer.Length);
                return encoding.GetString(buffer);
            }
        }
    }
    return null;
}

http://social.msdn.microsoft.com/Forums/en/netfxbcl/thread/ff6c07e2-9c36-4490-a989-f24dcff76145