Signs that your Hard Drive kicks the bucket, taking all your data with it:
– frequent crashes, especially while booting up
– frequent error messages while copying or moving or files
– disappearing files and folders
– long times to access folders and files
– scrambled files or folders names
– unusually loud sounds which you never heard before (clicking, repeated spin-up and spin-down)
In case your harddisk just kicked the bucket, try File Scavenger Data Recovery.