Do you think there are users of your application out there who want to search through a 45000+ lines combobox to find the city they want?

What is wrong with the following in btnAdd_Click ?
Dim total As Double = CDbl(txtNum1.Text) + CDbl(txtNum2.Text)
That way you don't need number1 and number2.
Now convert total back to text and...

Use a custom format:
Like so :

dateTimePicker1.Format = DateTimePickerFormat.Custom;
dateTimePicker1.CustomFormat = "HH:mm";
HH meaning 24 hour with 2 digits
mm meaning the minutes.

How would you enter time in a textbox? Which format would you use? How would you validate the input of the user?
I would consider a DateTimePicker control for that.

Dim rnd As New Random()

R = ListBox1.Items.Count - 1 ---> R = ArraList1.Count
ListBox1.SelectedIndex = Rnd() * R ---> int SelectedIndex =rnd.Next(0,R)...

Change ListBoxN.Items to ArrayList

NewcomplaintForm.vb ----> Visual Basic? ----> VB.NET

Handle the KeyDown and KeyPress events of a textbox.
Check if every key pressed is numeric.

Don't annoy a user.
When the action is save, save and nothing else.
Why not show him the latest Bond film after he did a save?
But if you really must : the last line in your save method, should be...

Are we talking about a DataGrid or a DataGridView here?

If I had an easy to sold application developed why would I tell you about it?
As an example : I can download almost 10000 applications on my iPhone for free or for a few dollars, look them up,...

My.Computer?
Where is the code where you try to use My.Computer?
Which error message do you get?
This is the same as telling me: "My car won't start, start it."

Teme64 points you to a thread where a question is asked some code is given and what was already done.
What you are saying Eyo is : "I HAVE AN ERROR, SOLVE IT!" That's why I came up with the car...

My car won't start!!! Help plz.

Which car?
What are the circumstances in which it won't start?
etc.
etc.

Please refrase your question.

Look at http://www.microsoft.com/express/
Find Visual Basic, download is free.

I think you need to check out the DropDownStyle property.
Set it to DropDownList.

A ComboBox, as it's name implies is a combination of a TextBox and a ListControl.
If you type an 'a' into the "TextBox" you will see that the ComboBox.Text property contains an 'a'. To put that 'a'...