Fix XAMPP MySQL server shutdown unexpectedly

IMPORTANT: do NOT delete ibdata1 file. You could destroy all your databases.

Instead, first try using the MySQL backup folder which is included with XAMPP. So do next steps:

1. Rename folder mysql/data to mysql/data_old
2. Make a copy of mysql/backup folder and name it as mysql/data
3. Copy all your database folders from mysql/data_old into mysql/data (except mysql, performance_schema, and phpmyadmin folders)
4. Copy mysql/data_old/ibdata1 file into mysql/data folder
5. Start MySQL from XAMPP control panel

Source: https://stackoverflow.com/questions/18022809/how-to-solve-error-mysql-shutdown-unexpectedly