Ringtone file cant be found to sync....

I have a few ringtones purchased through itunes on my old phone, since i have my new one, when i go into itunes on my windows laptop they show under tones, but when i then try to sync them an error message appears saying the original files cant be found!!! I dont understand why though...and how i can find them to sync to my phone. I have paid apple money for these and certainly arnt going to do so again. Please help.....