1.
How to transfer music to my iPod (& iTunes) {click on link}
2. iTunes can only import mp3, mp4 audio (m4a/mp4), apple lossless, aiff & wav files. iTunes cannot import wma, real, ogg vorbis, flac or monkey, or mp3pro files.
3. Might be fake music files. Check
Virus thread: Typical virus spam file sizes - Make a note of them (click on blue link to see).
If the songs did not show much id3 tag information or a bitrate, then most likely fake. Also might be deliberately corrupt spammed files also;
mp3 Bit-Rates Versus File Sizes (click on link)