Is it possible to convert VB.NET to excel VBA macro?

As Dave says, VB.Net and VBA are very different languages which share some common syntax - the framework behinds them is vastly different, and would not be simple to convert - especially without seeing the original code or having any idea what it does.

The other thing to consider is your "throwaway line":

Quote:

i can't use an application .exe

We have no idea why, but there are generally two reasons:
1) It's against company / establishment policy to allow unapproved executables.
2) It's an attempt to hide the executable from the user.

The first case means you shouldn't even try: if they catch you - and they will, they have been doing this for longer than you have - you will be subject to disciplinary action. In some cases this will mean they wave goodbye to you immediately ... Companies and institutions do take this kind of thing seriously.

The second case is a bigger problem: jail time, fines, public humiliation - it depends one what the code does or is intended to do. Loads of people take this seriously!

If I was you, I'd think long and hard before moving forward with any such project, even if it seems innocuous to you.

You would have to rewrite the code from scratch. There is no conversion tool that will do it for you.

Copying and pasting the VB.NET code into a VBA module will do you no good. The two languages are vastly different from each other making it impossible for a direct line-for-line conversion to work.

You would have to understand the intent of what the VB.NET code is doing and write entirely new code to accomplish the same task.