Try printing out the variables and the query before sending them off. Verify that the query and related variables are sound and correct.
Also, I'm not sure but it could matter that you had an apostraphe directly after the word 'LIKE'.
Then finally, add a mysql_error() command to see what happened.
$qry = "SELECT * FROM users WHERE upper($field) LIKE '%$find%'";
echo "Query: $qry<br />Field: $field<br />Find: $find<br />";
$data = mysql_query($qry);
echo mysql_error();