Tools are not found in the toolbox of asp.net core web application development environment.
Correct. This is the default behavior for ASP.NET Core and Visual Studio.
It is stated that there are no usable controls in this group and I tried several solutions like 'reset toolbox', 'show all ' but nothing worked. How can I have the toolbox with the tools I need to design my views.
You have not explained what tools you expect. If you are expecting ASP.NET server controls like a dropdowns and grids then I'm sorry to inform you these controls do not exist in ASP.NET Core. ASP.NET Core uses tag helpers.