OleDbCommand cmmd = new OleDbCommand("UPDATE trialtable SET userid=@userid, password = @password,testreport= @testreport,date12= @date12 where userid = @userid)", conn);
Error in your query stmt
OleDbCommand cmmd = new OleDbCommand("UPDATE trialtable SET userid=@userid, password = @password,testreport= @testreport,date12= @date12 where userid = @userid", conn);