Composer not working, how to work?

Question

Composer

The composer is broken on the project, it thinks for hours and does not end. As a result, new packages cannot be installed. Everyone who tried to fix it failed. In this regard, the question is - what to do next?
At the moment there is a task, it uses the library. It was installed by hand, first downloaded to an empty project, then copied to vendor.
How to be further? Add it to the git to drag it to the server? Surely someone had such problems, how did you solve it?