When you ask a question you need to provide some basic information
-Forum quick start https://forums.adobe.com/docs/DOC-5601
Mac or Windows, and EXACTLY which version of the operating system?
Recent Mac AND Windows operating systems have been known to cause "odd" problems
Are you using a computer Administrator account with full read/write permission?
Exactly which version of the program do you have that is causing problems?
What is the exact error message that you see?
i have a macbook pro.
Downloaded the latest software update yesterday macOS Sierra 10.12.3 (16D32)
Ever since my lightroom won't open!
Do you know what version of Lightroom is installed on your computer?
Are there any error messages that are displayed? If so, what is the exact message that is given?
You say that Lightroom doesn't open. Does anything happen when you try to start Lightroom. Again, details are important. Just saying that Lightroom doesn't open doesn't tell us enough about what is happening. Please take the time to explain..
So the version i have is Photoshop Lightroom CC 2015 Release.
When I open it it just turns into a rainbow, and it never opens.
Tried to restart the computer many times, but nothing happens.
I'm sorry. What do you mean when you say, "It turns into a rainbow?" What does?
Sorry I mean the cursor turns into this 'Not Responding' Rainbow which displays on any Mac.
I guess if I was a Mac user I would have understood that. Have you installed the latest update (CC 2015.8)?