Manual Backup

Following the path you got (i.e., manually copy files), what you could do is run playonlinux for the first time, let it generate the default .PlayOnLinux folder, then quit the application, delete that folder and replace it with your own .PlayOnLinux folder. Then restart playonlinux and you should be able to use all of your applications that you were using before. You may have to tweak a few settings if you were using a different version of playonlinux before, but it should be a usable solution.

Note: You must remember to let playonlinux run once before you quit it and copy your folder across from the backup drive. You mention you copied it before you ran playonlinux- this is the main problem, as playonlinux will overwrite the folder, as you have found out.

PlayOnLinux Vault

However, in the future you could use the 'playonlinux vault' (see screenshots below), which can be used to both backup and restore your applications. It is accessed through playonlinux > plugins > PlayOnLinux vault. It does backup the entire wine prefix that the application is installed in and all the other necessary playonlinux settings. It is a plugin, but is now installed by default. It is easy to use as you are guided through the various stages of the backup or restore.

The only downside is that the plugin takes a while to compress the backups, but the latest version of the plugin has an option to disable compression, which will improve speed and performance of the backup. Disable and remove the vault plugin in pluginmanager and then download the latest version from the official site and install it and enable it using pluginmanager. Now reload playonlinux and you will get the option to not use compression (see screenshot).

There are perhaps other ways of backing up your programs, but the two solutions discussed should be useful for you.

Screenshots from the 'playonlinux' vault plugin:

To install WMP11, you'll need 'cabextract' and the WMP11 installer. Also make sure your wine version is set to XP.

sudo apt-get install cabextract

1. Open a terminal and type:

   cabextract "/location/to/WMP11/installer.exe" -d $HOME/WMP11
   

   (Obviously, you'll have to write the real path/location to WMP11 file)

2. Change to the new created dir:

   cd $HOME/WMP11
   

3. Install WMP11 codecs:

   wine wmfdist11  
   

   (You'll have to press Ctrl+C (on terminal) after it finishes installing)

   wine wmp11
   

   (Also press Ctrl+C after it finishes)

4. Set Wine version to 2003 and run WMP11

   It will pass the genuine check but it will crash. You'll have to kill the process (open the 'System Monitor' and kill setup_wm.exe)

5. Run WMP11 again and click continue.

   Now WMP11 starts, although you can barely see it. To fix it click on 'File', press right and select 'Mask Mode'.

There you go. WMP11 is installed and running.

reference here

But according to Wine HQ windows media player is rated as garbage

For further reference here