You might as well start with the .WAV file you were sent originally. Load it into Audacity Press Ctrl+A (or use mouse, menu: Edit | Select All) Then select menu : Effects | Amplify
The Amplifier effect will work out the maximum gain possible without clipping. You might as well accept that and let ot do it.
Then from the File menu, "Export project as .WAV", tell it where to save the .WAV file and you're done.