Narrow down the problem.
Try another headset on the existing audio device.
Try the headset on another audio device.
See if the problem follows the headset or the audio device.
You can also put the headset on, start the music (even if right ear only) and whle listening gently wiggle, twist, bend the wires all along their length.
Could be a break along the way and the cable manipulations may make temporary contact enough to locate the break. Pay close attention to the plug and the connection point(s) into the headset.
And you can also go into the audio settings via the speaker icon (usually lower right screen) and go into "Playback Devices". Check all of the various tabs and properties. Could be misconfigured with respect to balance.