Look at query to see if it's valid and look into any exception messages. One problem I can see is that
"' WHERE ID = '"+ txtForID + "'";
"' WHERE ID = '"+ txtForID.Text + "'";
As already suggested you should use parmeterised queries, and there may be other issues apart from the one above. Just dumping your code, not giving error messages or error lines and saying "doesn't work" isn't giving anyone enough information to help you.