What make and model mp3 player?
Would not expect that a reset would lose your music but without truly knowing the problem the lost of data is a possibility. Could lose your music no matter what.....
The key is to identify what the flashing may mean or indicate; e.g., low battery, corrupted memory....
Do you have the User Guide/Manual? Look in the Troubleshooting Section.
Visit the player's manufacturer's website: Forums and FAQs. See if anyone else has reported a similar problem or related question.