Does this restore lost quality?

No. Converting a compressed file to WAV can't recover detail already lost, but it gives you an uncompressed working file.

Audio to WAV

Convert compressed audio to uncompressed WAV.

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Convert MP3, M4A, OGG and more to lossless-container WAV (PCM), useful for editing and mastering. Processed locally in your browser.

Open the Audio to WAV tool and add your file. It's processed in your browser, never uploaded.
Adjust the available options to get the result you want.
Download the result. There's no sign-up, no watermark, and no size cap.

Does this restore lost quality?: No. Converting a compressed file to WAV can't recover detail already lost, but it gives you an uncompressed working file.

Other private, in-browser tools you might need.

Convert audio files to MP3, private, in your browser.

Compress bulky WAV files into portable MP3s.

Convert M4A audio to portable MP3.

Convert OGG audio to portable MP3.