How to increase volume and decrease the muffled sound of a recorded track

I recorded a cassette and the beginning portion of the track is low and muffled. I’ve tried the recommendations for amplify and the envelope, but neither worked. . Any ideas?

I’m new to the program so I have limited knowledge.

Thank you in advance!

Try* boost treble … https://manual.audacityteam.org/man/bass_and_treble.html

(* if there is no treble to boost, then that won’t help).