Amarok crashed on me yesterday and I  uninstalled it and downloaded everything fresh from the source. This time, however it is acting even more buggy!  It won't add music to my collection.  I tell it to scan the folder where all my music is, and it just starts scanning but never makes any progress, and then the scan bar just disappears as if nothing ever even started.  It can play music just fine, but it won't add anything to the collection.  I think the whole problem started when I changed the name of my music folder yesterday, but I've tried changing it back, and that doesn't solve the problem.  Any suggestions?  How can I get Amarok to find all the files that once were in my collection?

Is your collection on a network share, using samba? IF so, check the amarok wiki (the url is mentioned many times elsewhere on here, and I don't have it handy) for information on making sure your shares are mounted properly.

No, the whole collection is on my hard drive.  It's really odd, because before all these errors started happening yesterday everything worked fine!

ok, when you uninstalled, did you also trash your amarok config? You can try renaming or deleting ~/.kde/share/apps/amarok/ and ~/.kde/share/config/amarokrc and starting amarok. You should be greeted with the first-run wizard.