First go to this website and download your desire xampp version file. Don't download Installer or Portable version. Download zip version. Example: xampp-windows-x64-7.2.34-2-VC15.zip
Now go to your old xampp folder. you will see a folder name mysql , rename the folder like mysqlold.
Now go the folder you just download. you will see mysql folder. Copy the mysql folder and paste it to your old xampp folder. That will solve the problem of MySQL shutdown unexpectedly.
But if you have database in your old mysql, just go xampp->mysqlold->data folder and copy all the database file and ibdata paste it to your new mysql folder that you just pasted to your xampp folder.
That's it Enjoy 😄