UnityEngine.UI missing

I am new to unity and I am trying to make a score that counts collectable items such as coins. For that I need to use UnityEngine.UI in a C# script but it doenst exist. There is UIElements but that doenst seem to be the thing I need. I have been looking for answers everywhere for 2 days but couldnt find anything. some people have the same problem but all they say is to remove the UI and install it again. Im not sure how to do that. I tried hitting the "remove" button in the package manager but that didnt do anything, it is just grayed out now. Thanks in advance!