Error: MySQL shutdown unexpectedly.
Instead, first try using the MySQL backup folder which is included with XAMPP. So do the next:
1.Rename the folder mysql/data to mysql/data_old (you can use any name)
2.Create a new folder mysql/data
3.Copy the content that resides in mysql/backup to the new mysql/data folder
4.Copy all your database folders that are in mysql/data_old to mysql/data (skipping the mysql, performance_schema, and phpmyadmin folders from data_old)
5.Finally copy the ibdata1 file from mysql/data_old and replace it inside mysql/data folder
6.Start MySQL from XAMPP control panel
And, voilà!