Merging two Apple ID accounts in iTunes

I have had an iTunes account for years. When I needed a new laptop (PC) a year ago, and set up iTunes, I must not have been paying close attention but it defaulted me to using the. Apple ID i started AFTER I started using an iPhone (different than the ID I had been using for some time with iTunes). When I realized that I had lost my playlists, etc. I converted back to using my original ID on the iTunes app. Now in the Account info I see both listed (grayed out) and I suspect that there is music I purchased on the Apple account that I cannot see.

How can I merge music from two accounts?