If everyone, including the EFS Recovery Agent, is unable to access any encrypted files, you might have altered or deleted the NtfsEncryptionService value name, a string value containing the encryption service that the NTFS files system uses, at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem. The data value should be Efs, the Encrypting File System which is included with Windows 2000.
To encrypt a file or folder on an NTFS partition, use Windows Explorer to right-click the name of the object and press Properties. Use the Advanced button and check the Encrypt contents to secure data box.
You can also use the CIPHER command.
NOTES: If you intension was to disable EFS, see: