Focus on a textbox whose name is stored in a variable in vb.net

Hello everybody,

I have many textboxes in my form
In the lostfocus event of every textbox I store its name in a string variable called LastUsedTextBox

I also have many other controls on my form
I have a button

If the focus is on any other control which is not textbox then I want to have focus on textbox whose name was previously stored in the LastUsedTextbox (String) by clicking on the button

Does any one knows the answer.

Thanks in advance.