first sry for my english i know that my gramar is not the best

hi guys i'm first time here and i could really use your help ,if you can help me ... in any case this is my story... so i have an iphone and it was great until today... i had instaled windows xp on my computer ( SP2 ) and it worked fine i could use my itunes, sync my iphone and it was really great ( couldn't complaine) but my windows was slow so i reistaled windows with servis pack 2 again , and i instaled itunes again, and made a new libary , so i got all things good and start to sync , so it started and i thoght that it was all right and in 2 min or so , it just stop sync and like that every time i try, i can't put single file in iphone , and if i put some file by some luck , some mp3 files that before worked fine they don't want to play on iphone but on itunes works fine... so i tried really everything that i could remember and nothing, so guys anyone,can you help me please !!!