Windows 7 Windows Media Player 12 won't update the library when I add an item to the library - please help!

The WMP troubleshooters in Control panel ought to sort your problem out but ....

I had the problem of a suddenly empty library in Windows 10 and perhaps that's where your problem started as I have only seen this problem reported in Windows 10 or in computers that have reverted from Windows 10 . 

• The WMP troubleshooters in Control panel failed to fix things.
• Unloading then reloading WMP [Control panel, Programs & features, Turn Windows features on or off, Media, WMP entry] did not fix it either.
• So I fixed it manually as described below.  My fix ought to have been a waste of time because the WMP library troubleshooter ought to have recreated the WMP database anyway.

But first I note from your problem description that you have WMP set up to retrieve information from the internet.  If that is deliberate then fine but if you do not use the internet to fill in your audio file properties then removing those settings reduces the number of things that can go wrong in future. 

• See Organise, Options, Library tab - clear the Retrieve info .... from the lower part of the dialog.
• See Organise, Options, Privacy tab - clear the internet-related items in the upper part of the dialog.

1  I played around with other user accounts until I found one in which the WMP library was working correctly.  I went to %LOCALAPPDATA%\Microsoft\Media Player for that good account and compared it to the corresponding folder for the bad account. 

If you do not have another local user account [not an MSAccount] then create one for this fault investigation.  You can easily delete it later but, if you do not have a spare local Admin-level account already, then it would be worth raising it to Admin-level, password protecting it and either making a Password reset disk or writing the password down somewhere.  A spare Admin-level account would be an essential recovery tool if you ever suffered from user profile corruption in the account you use for your day-to-day tasks.

2  In the bad account, the main database CurrentDatabase_400.wmdb was only 1MB but in the good account it was 67MB.  In the bad account, the file wmpfolders.wmdb was missing altogether.  There were also other .wmdb files in each folder but I never noticed anything significant about them.

3  I copied all the *.wmdb files from the good account into the bad account even though there were differences in the folders I intended to monitor. 

4  I then opened the bad account's WMP and it started running its normal updating procedure and all looked well.  To test this further, I changed the monitored folders to suit what I actually wanted for this particular user account and I played around adding & deleting files in the monitored folders.  I also rebooted to make sure it could survive that.  Everything is now working correctly.  I had one apparent glitch when it did not seem to respond to a change in monitored folders until after I closed then restarted WMP but that might well have been impatience on my part as it subsequently performed correctly for every change I made.

5  WMP in the no-longer-bad account is updating correctly and its *.wmdb files in %LOCALAPPDATA%\Microsoft\Media Player reflect that.  I do not know which of the .wmdb files forced it to start behaving itself but I suspect it was the main one, CurrentDatabase_400.wmdb [I looked through the contents of wmpfolders.wmdb and it seems to be derivative as if CurrentDatabase_400.wmdb was controlling it].  I decided that copying all the files was the safest thing to do but would try copying just CurrentDatabase_400.wmdb if it went wrong again.

6  I have now added the *.wmdb files to my routine backups so I have the latest possible state of them if I ever need to fix the fault again. 

If this does not fix your problem then create a new question of your own [Participate, Ask a question at the top of the page].  New questions get a lot more attention than old ones.  Make sure your problem description identifies all the fault symptoms and all the steps you have tried in your investigation including what happened when you tried each one.  make sure you include the comment about having reverted from Windows 10.

All the best,

Denis

Sadly the link to the answers forum is broken, I guess that should no longer surprise me.

This did not work. 30 minutes ago I had a library of 30,000 songs. For some reason Media Player finished updating from the Internet and then deleted the entire catalogue. The files are still there, and get entered if I play them from Explorer but the library is not rebuilding.

I can't tell whether the computer is punishing me from un-installing Windows 10 or for migrating from XP! I know that 15 years ago I had a stable platform and now I don't.