mysql keeps crashing

[knutsford]

I have had to download xamp twice today:( The Mysql wouldn't load this morning so I downloded a new version and copies two of my sites over to the new version plus the data for the two site to data under mysql. Every thing was fine until I closes xamp down and tried to restart it again. Mysql didn't load again. I looeked as though it wanted the data for the rest of my Sites but it still didn't start after I copied those over. To stop it happeneing again what should I copy to MySql? Everything under the Data library or do I need to copy over anything else? Thanks