iPhone music no longer synced with PC
You may want to check out some of the suggestions from this Apple.SE question. Basically, make the music libraries of your two computers (PC and laptop) available to your iPhone via either:


iTunes Home Sharing
iCloud (if your library isn't too large OR you don't mind paying)


This article also suggests iTunes Match as an option.

Another alternative is to merge the music libraries from your two computers:


Copy the music from one machine to the other that your phone is currently syncing with
Copy the music from your iPhone to a computer - see this Lifehacker article for suggestions for several platforms (Windows, OS X, Linux)


Lastly, you can manually manage your music on the iPhone, which prevents a sync altogether and allows you to drop music in from multiple computers. This Apple Support article explains it in detail.