how to fix a project that wont work after importing an asset?

i import an asset from asset store, and it notices me that it will import the whole project and changes my setting, i click import, after the importing done, my project just wont work like it was, now i dont know how to fix it, when i click play, there is no error message, i already check the axes(button input), build setting, the old script(from my project), and check if there a script with the same name, check the scene name,

can someone pls help me,
im still new at unity,
and sorry for my bad english.

Without more details, about what’s wrong, people probably can’t give you pinpoint advice so the answer to the question you’re asking, the way you’re asking it will probably be “everything”.

This is the kind of problem that is difficult to fix but easy to prevent. Get yourself some version control. A lot of people like GitHub. I use Visual Studio Team Services. Last time I checked, there was a way to use either for free. You can also just install git or Subversion on your local machine.

Whatever the case, if you use version control and check in regularly, the answer to this question would be “undo your current changes in version control”.