Iphone syncing

Guys i made a mistake syncing iphone with another itunes library and all of my music was gone from ipod.Now does anybody knows how to sync it with my macbook pro's itunes to get my music back in it,without having to erase the applications i have downloaded since now.Because it prompts a message that it will erase my apps when i execute sync music,that's why i am asking.Please any help would be grateful,thanx

Go ahead and re-sync with your Library. Assuming that you actually bought the Apps in question via your iTunes account you won't have to pay for them again. Apps don't work like music, you can download them multiple times to the same device for free.