These are legitimate copies, paid for -- and I can't download new copies. There are over a dozen books missing, some of them bought, some downloaded from Gutenberg. (ADE seems to eat all the Gutenberg editions.) I hate this DRM. All it does is make things harder for honest users--the pirates laugh at this stuff (I know, I'm also a writer.)
What's going on here? Is there any way to get the books back? This seemed to happen after I went from Vista, which stank, to Windows 7, which is even worse, which I didn't think possible.
You can easily redownload the Gutenberg books.
I suggest you don't let ADE get near them, but use the free Calibre software to read them on PC or transfer to eReader.
Unfortunately, ADE still has a nasty habit of crawling over eReaders connected to it and wasting lots of time processing books on the device that have nothing to do with Adobe, DRM or ADE,
If you still have the .epub files (or probably even the .acsm files) for the bought books you can read them on the new computer.
You need to register ADE with the AdobeID you used when you first bought the books.
The Adobe DRM system is there to hinder, not to help. It does not keep copies of your books or the fact that you own them.
If you have lost the original files and don't have any backup, I am afraid you have the digital equivalent of a real book consumed by flame.