vb.net program to rename all files in a folder

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$17
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$10 - $15

Project Description:
i have 1500 files in a folder. they have names such as chemistry1.html, chemistry2.html etc all the way to 1500. i need them all renamed using this format:

chemistry1.html RENAMED TO chemistry0001.html
chemistry20.html RENAMED TO chemistry0020.html
chemistry300.html RENAMED TO chemistry0300.html
chemistry1050.html REMAINS THE SAME

so what is happening is that the numeric part of the filename is changed from an ordinary number into a four digit number, with leading zeros unless it is already a four digit number.

It should be a very simple application, with one button to select target folder and another button to start the process to finish. It should be written in VB.NET 2008 or older and I want the source code.

Skills required:
.NET, Visual Basic
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