the i phone cannot be synched because the iphone cannot be found

I tried to synch a new playlist last night and when I went to listen to it none of my music was on my iphone. The folders were there and the album and artist names but when I clicked on them individually there was no music. Not sure how but I managed to get the music to show back up tonight but the new plalist is not there and when i try to synch (wirelessly or connected) it either says unable to synch iphone because iphone could not be found or unable to synch apps because iphone apps can not be determined. Either way, the new playlist and the new content is not showing up and the phone shows the last synch as being June 2. Any help would be appreciated.