How to generate .ascx.g.cs file manually

Please find the below steps to generate .ascx.g.cs file manually for your Visual webpart:

1. Ensure the project's site URL is specified correctly and it's valid.
2. Go to your Visual webpart  => expand the visual webpart file => right click on .ascx file => click on Properties => Update the "Custom tool" to "SharePointWebPartCodeGenerator".
3. Right click on .ascx file and Click on "Run Custom Tool".
4. Go and check, your .ascx.g.cs file will be generated.

Hope these steps solved your issue. Happy Coding.