MP3 file will “lose” in certain situations. For example, it may lose a MP3 file if MP3 player software is forced to quit unexpectedly, or if your computer has a power interruption while you’re playing, or if you close the file without saving changes,or virus attacks,or fomatted by a mistake,or deleted by a mistake operation.
If you format hard drive and deleted MP3 files by a mistake operation will loss data,you need data recovery software to recover MP3 files.
MPEG-1 Audio Layer 3( MP3 ), is a patented digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard of digital audio compression for the transfer and playback of music on digital audio players. MP3 is an audio-specific format that was designed by the Moving Picture Experts Group as part of its MPEG-1 standard.
The use in MP3 of a lossy compression algorithm is designed to greatly reduce the amount of data required to represent the audio recording and still sound like a faithful reproduction of the original uncompressed audio for most listeners. An MP3 file that is created using the setting of 128 kbit/s will result in a file that is about 1/11th the size of the CD file created from the original audio source. An MP3 file can also be constructed at higher or lower bit rates, with higher or lower resulting quality. The compression works by reducing accuracy of certain parts of sound that are deemed beyond the auditory resolution ability of most people.

The MPEG-1 standard does not include a precise specification for an MP3 encoder, but does provide example psychoacoustic models, rate loop, and the like in the non-normative part of the original standard.
Decoding, on the other hand, is carefully defined in the standard. Most decoders are “bitstream compliant”, which means that the decompressed output – that they produce from a given MP3 file – will be the same, within a specified degree of rounding tolerance, as the output specified mathematically in the ISO/IEC standard document.
Several bit rates are specified in the MPEG-1 Layer 3 standard: 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256 and 320 kbit/s, and the available sampling frequencies are 32, 44.1 and 48 kHz.

When performing lossy audio encoding, such as creating an MP3 file, there is a trade-off between the amount of space used and the sound quality of the result. Typically, the creator is allowed to set a bit rate, which specifies how many kilobits the file may use per second of audio. Using a lower bit rate provides a relatively lower audio quality and produces a smaller file size. Likewise, using a higher bit rate outputs a higher quality audio, but also results in a larger file.