I'm writing this for the HTC Desire, but it
should work for all other models and most likely all other Android phones. The process was identical for my old Sony Ericsson C905 and my girlfriends SE W580i.
The problem is the phone is looking for the album art within the track itself. So, we need to embed it, because having a .jpg file in the folder will not do. The phone does not look for the album art there, so it's not going to find it!
1. First you need to download a freeware program called
mp3tag. Install it and run the program.
You may donate to mp3tag if you like the software. I've been using it for quite some time and I gave them $20. Not much, but I hope it helped them
2. Secondly, drag and drop all the music that does not have album art stored
within the file. Highlight a number of tracks, best to do this an album at a time. Now you can either right click in the empty album art box like the image below and find the album art on your computer.
Or you can highlight all the tracks (again, best to do this one album at a time) and click "Tag Sources" on the menu bar and choose "Cover Art" then pick either amazon.com or amazon.de. It doesn't really matter which.
Now the album in my screenshot wasn't found automatically by the amazon search, but most other albums are.
3. If your albums aren't found via the amazon searches you need to the first part of step 2. However, you still need your album art. A good website (that did have the art for my example album) is:
Albumart - CD and DVD cover searchengine
4. Copy your tracks to your phone!