Likely, if you have appeared here to this page you are having the problem I had for the past hour or so. Intellisense is not working in Visual Studio. Well lucky for you, I figured out the solution to fix this issue after searching the entire web. So you don't have to search the web anymore, I will tell you how I fixed the issue.
Step 1:
Close Visual Studio
Step 2:
In Unity, go to Edit < Preferences < External Tools (left part of the Window)
Step 3:
In External Tools...
Intellisense Not Working with Visual Studio (Fix)
Step 1:
Close Visual Studio
Step 2:
In Unity, go to Edit < Preferences < External Tools (left part of the Window)
Step 3:
In External Tools...
Intellisense Not Working with Visual Studio (Fix)