i just pre load the sound track and almost all for SP and there is 24+- so it means (by the names ) that there is 20 levels?

Nope that means there is an assortment of tracks that play in each level!
different music in different mission/areas on map... etc
There is at least 7 levels in singleplayer

i dont think there's 20 or 20 some level! Crysis 2 was long, 22 level, if Crytek goes back the good old recipe, then every mission will have at least 2 even 3 levels! Then we'll have 14-21 level!

deluxehunter how did you get the soudntrack i dont have it =(

There are 7 levels in the game, plus a tutorial for all the nanosuit functions.