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The problem may be owing to the playlists being corrupted. If so, then even when you try to play one or the other again, it will again fail, for these two playlists.
Also... your device might need a reset, if it has locked up. Or at least, power Off the device, then leave it that way (unplugged from the power too) for 1 hour, at very least, and then try it again only after that long or longer.
(Let me know what device you have, if the above does not get it working again... there are other resets, specific to devices, that can be tried, for instance. Maker name, and model, would identify your device to me. Thanks.)