That's better. It so much easier to help someone who is telling the
purpose of the question instead of just asking for how to do it the way
he/she thinks that it is done.
The best validation for numeric values and dates is to actually try to
convert them. Use DateTime.TryParse and Int32.TryParse methods for
instance. If you use a parameterized query (which you really should),
you would want them converted anyway.
To validate string data you can use RegEx. To verify that a string only
contains alphabetic characters you use RegEx.IsMatch(theString,
"^[A-Za-z]$").