Reinstall worked. Problem was with all file types flac and MP3.

What file type and have you tried rescanning?

The program stopped playing music selected from lists in MM metro 8.1 today after upgrading to sync and lyrics. Previously fine. It will play when selected from file manager. MM W8.1 full version works. Both are on the same computer. The music files are stored on network computer (HP server). MM 8.1 metro on RT works on my tablet looking at same music files. Any ideas?