Isabella Saggese , Try reset again, hold power button 10-20 sec's and repeat a bunch of times if need be. Still no luck, another reset procedure can be found at the 1st link below to try. If possible to obtain warranty, return for repair/replacement. If need be find a link #2 to show how to disassemble to check loose connections/components inside the headphones, just be careful delicate wires and components and follow instructions carefully and pay heed to the warnings. Not comfortable working on the device yourself, have a local computer/electronics repair shop have a look, diagnose and estimate repair. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
https://www.youtube.com/watch?v=m2rB3vsoEtU
[guide|54520]