A Few Questions

I have a few scenarios that this question applies to.

First, a few albums on my iPhone 4S have lot their album artwork and now only show the default gray music note instead of the appropriate album cover.

Second, there are a few album artworks that I would like to replace with more HD versions.

I have tried deleting the albums from my iPhone 4S only to find that iTunes won't let me add the albums back to my device which leads me to the next questions.

For some reason, iTunes will not allow me to add albums to my iPhone 4S.

The albums I've tried adding were manually deleted off of my device, and when I try dragging them from iTunes onto my phone, nothing happens. iTunes does not say that the songs are on my iPhone 4S anymore and doesn't mention anything about any duplicates being added.

Now for the last question.

There are a few songs on my iPhone 4S that will play the wrong song when selected.

For some songs, when I click the song to be played, it will still show the proper song name, artist, time, artwork, etc. However, an entirely different song will be played.

Most of the time, the song that is played will still be played when I choose to play that song, so it's not as if they've switched for some reason. I have also noticed that the song played won't even be on the same album as the one chosen.

I'm not sure at all as to why this has occurred and am unsure of how to fix it.

If you are able to answer any of these questions, please reply with any solution you may know.

Thanks so much for any help anyone can give!