Hi,
I have LimeSuvey installed on windows Server 2008 R2.. I am going to upgrade to windows server 2019. Would this upgrade break Limesurvey or would it still work fine?
I also have Apache 2.4 , PHP 7.1.9 and MySQL Server 5.7 . what's the most recommended version of Apache, PHP and MySQL  to upgrade to them 
Thanks!!
 

To run LimeSurvey 5, you need at least PHP 7.2.

so would i lose all my surveys and the data if i upgrade the OS on the server to 2019, PHP to 7.2+ and mysql? or what should i do to not loss anything?

I'm don't know anything about Windows Server, but you should always do a database backup before a major update.