Help!Problems about opening the Arduino IDE on Mac

Basically, I can't open the Arduino IDE on my MacBook which it stated that the library folder is lost, it needs a new folder and after that it will stop mentioning itself as a third person.

Delete or rename: /Users/(username)/Library/Arduino15 (a.k.a. ~/Library/Arduino15)
(Note: The 'Library' folder is greyed out in Finder. The folder can't be opened with a double-click. To browse the contents of 'Library', ctrl-click on it and select "Open in New Tab" from the pop-up menu.)

Then install the latest version from:

Rest assured that all of your sketches and third-party libraries will be left untouched.

johnwasser:
Delete or rename: /Users/(username)/Library/Arduino15 (a.k.a. ~/Library/Arduino15)
(Note: The 'Library' folder is greyed out in Finder. The folder can't be opened with a double-click. To browse the contents of 'Library', ctrl-click on it and select "Open in New Tab" from the pop-up menu.)

Then install the latest version from:
https://www.arduino.cc/en/Main/Software

Rest assured that all of your sketches and third-party libraries will be left untouched.

Thank you for your reply, but why I can't find any "Library" folder under my user folder?

Jerry_Peter:
Thank you for your reply, but why I can't find any "Library" folder under my user folder?

What version of MacOS are you using? I'm using 10.12.6 and have had a Library folder for YEARS. If you don't have a Library folder, that would cause all sorts of problems. Maybe the only way to fix it is to re-install the OS?!?

johnwasser:
What version of MacOS are you using? I'm using 10.12.6 and have had a Library folder for YEARS. If you don't have a Library folder, that would cause all sorts of problems. Maybe the only way to fix it is to re-install the OS?!?

johnwasser:
What version of MacOS are you using? I'm using 10.12.6 and have had a Library folder for YEARS. If you don't have a Library folder, that would cause all sorts of problems. Maybe the only way to fix it is to re-install the OS?!?

I finally find the "library" folder in the user folder and I now solve the problem following your instruction. Thanks a lot for your help!!