Hi Oto,
[quote user="Oto"]How to re-register Microstation?[/quote]
Particular dll files (libraries) can be register, not MicroStation itself.
[quote user="Oto"]Unable to run C# Add-in[/quote]
Is it yours add-in and you have a source code or you are a user only?
[quote user="Oto"]it throws error Class not registered[/quote]
Is there any exception log available? It would help to track down what library is not registered.
With regards,
Jan