In the era of information and technology, everyone has personal data, such as bank card password, client list and identity card number. As long as we have data, data loss problem is unavoidable. In the society, no one has the obligation to remind us that we have to protect client list, credit card number, transaction record, etc. However, the government, insurance companies and various regulating organizations will ask people to obey the related rules of data management. However, this is not enough, and we should positively protect data. Three basic methods are offered in order to protect data. The first method is to backup crucial data. To backup data is to store the copy of data to other storage devices. Backup can be classified into 2 types: full backup and incremental backup. The second one is to set up permission. In Windows XP, Windows 2000, Windows Small Business Server 2003, Windows Server 2003 and Windows 2000 Server, we can set different levels of permissions for different users according to their roles and responsibilities instead of providing all users with full access to “Administrator”. The third method is to encrypt data. Data encryption, also called cryptology, is a technology with a long history. Data encryption means converting plain text to cipher text through encryption algorithm and encryption key. Data encryption is the most reliable way to protect data in computer system till now. After users adopt cryptography, information hiding can be realized through encryption so as to protect data. Combining these three basic methods, most enterprises can greatly guarantee the data security. Since data is very important to us, we should pay much attention to data security. Otherwise, data loss may bring us huge losses. For example, Diana, a hard-working employee of a company, once sent a file which contains 5000 medical records to her family Gmail account, intending to analyze them after work. But unfortunately, her son was playing computer at that time, and he was curious about the file he received. He sent this file to a friend for they was about to do a homework named “My Mother’s Work”. The father of his friend is a local newspaper reporter. What a coincidence! This father realized that it was a confidential information leakage incident, so he reported this to the authority. As a result, Diana’s company spent 1.2 million dollars (204 dollars for each medical record) to compensate for the losses. This shows us how important data security is. However, if we unfortunately lose our data, what should we do to greatly reduce the losses? There are mainly two methods: turning to data recovery companies and using data recovery software. Turning to data recovery companies can help us recover lost data, but data recovery will cost us a lot of money and we have to worry about data leakage. Thus, we’d better use data recovery software to recover lost data by ourselves.