Songs in library will not play - (!) - worked yesterday - what happened? How can I fix?

Question

"Original file cannot be found" error message when I click to play.   I have my music on an external HD.  It has been thus for the past 3 years.  Something happened and when I "Get Info" the songs now have file://localhost:/C:/users/........... and not F:\Music\Hendrix..................  I am not sure why the iTunes decided to rename all 15,000 of the songs in my library with this new location but if I delete iTunes and download it and install it....all of my playlists will be gone.  I know as I did this a year or so ago.  I went to the Apple site and they say to move the XML folder to the desktop and delete the Library...then import the play list.  I did this and it imported just 1,600 songs.  So I junked that and recovered the library with the above file location issues....I am back where I started.
iTunes had no problem renaming all my songs in the playlist to the above file://localhost blah blah blah....there must be an equally easy way to select all the files and just tell iTunes they are on the F:\ drive.  Yes???
Spent 5 hours trying to figure this out - not a techie - going slowly insane.

Answer 1

turingtest2 wrote:
The direction of the slashes in the two forms of address isn't important, that is how they are supposed to be.
****Thank you, I did not know that.
Starting here:
file://localhost/C:/Users/<name>/Destop/iTunes/iTunes Media/Music/iTunes Media/Music/<artist> <album> <songname>.m4p or .m4a
I'll take it you mean:
file://localhost/C:/Users/Susan/Desktop/iTunes/iTunes Media/Music/iTunes Media/Music/<Album Artist>/<Album>/## <Name>.<Ext>
so the obvious anomaly (ignoring the suspected typos)
****oops!
is that there are extra layers of folders and a different main path from the standard windows location which would be:
C:\Users\Susan\Music\iTunes\iTunes Media\Music\<Album Artist>\<Album>\## <Name>.<Ext>
****I do have an iTunes folder in this location, from when I downloaded the new version post-crash, but there is no music in it. I named the Library iTunesBlank.
Your files that play are in:
C:\Users\Susan\Desktop\iTunes\iTunes Media\<Album Artist>\<Album>\## <Name>.<Ext>
**** yes
Do I take it that the actual location of ones that don't play are also in this form?
****no, they are the ones with the localhost prefix and the extra layers of folders
Assuming I've understood the problem correctly then the next salient question is does the folder:
C:\Users\Susan\Desktop\iTunes\iTunes Media\Music\iTunes Media exist?
****not quite: here's the path - C:\Users\Susan\Desktop\iTunes\iTunes Media\Music ... in that folder are more folders with artist names from CDs I've burned, voice memos, compliations -- these all play.
There are also: iTunes Preferences, Library Genius, Library Extras, Album Artwork, Automatically Add to iTunes and Library -
Genius and Extras have the .itdb suffix, but Library with today's date is .itl ... but strangely, when I search for *.itl in Windows, this library does not come up. The others - LibraryBlank (the one in the Music, not Desktop folder), the one I copied over from my backup media, and the one I named Corrupt on June 14, do.
Would you also check that your library file, iTunes Library.itdb, is in the folder C:\Users\Susan\Desktop\iTunes ? You can check this is the active library by making sure that it has been modified today (assuming you've accessed iTunes).
****The only file on my system called iTunes Library.itdb is the  iTunes application!  Genius and Extras also have that suffix.
Thank you so much for your continued assistance!!!
DM2