how do i get quick time to work on my mac

Im trying to open a quicktime file and can't how will it work

Which version of QuickTime? (QT7 or QTX?) What kind of a file? (What file extension, video compression format, audio compression format, file source?) Which MacOS? (High Sierra, Sierra, El Capitan, Mavericks, Mountain Lion, Lion, Snow Leopard, Leopard, etc?) Are you getting any error messages that might be of some help in determining what is wrong? How are you trying to open the file(s) in question? What is the system doing when you try to open files? (Is it trying to convert the file? Does the QT media player crash? Does it play audio without video or video without audio? Does the player "lock up?") Do the files play correctly in alternative media players like VLC?

Please be more specific regarding your problem or upload a sample file for examination.