Your issue is this section of code:
x_id = myReader["x_id"];
fullname = myReader["fullname"];
email = myReader["email"];
The Data reader stores the objects as "object" types and you are trying to assign them to strings.
You could do:
x_id = myReader["x_id"].ToString();
fullname = myReader["fullname"].ToString();
email = myReader["email"].ToString();
But be aware when you are handling different types you need to do the appropriate conversion.
Such as:
If your ID was in fact an int instead of a string
x_id = Int32.Parse(myReader["x_id"]);