It will be much easier if you do provide some more information:
Name of Product and version such as Magix Music Maerk 15 or 16 etc.
Windows xp, vista or windows 7 do you use.
Did you install your program properly?
Ok try this easy method first, if you use Magix Music Maker in that case click on "Y" key on keyboard of computer when Magix Music Maker is on. Then locate Reset Soundpool and click ok. It is better if you re start your computer and then use Magix. Now, you will have to add styles from Add styles.