Netbeans autocomplete stopped working?

Question

I\'m using Netbeans 6.9.1, everything was just fine however suddenly, it has stopped detecting any changes made to the code, e.g new variables, functions, etc. If I try to refac

Answer 1

tools>plugins>installed

then find the Java SE,
right click and Activate enter image description here

this works for me on netbeans 12.2