They are probably just getting old. Cut them all off and the small shoots will grow from the bottom - it takes a lot to kill off mint, so just go for it!

Mint is an outdoor plant and your kitchen is too hot and dry for it. Put the pot outside the back door where it will be cooler and get rained on.

I grow mine in a pot outside all year. It dies back then regrows again. I live in Scotland so it is ok with the cold but not a hot kitchen.

I agree with Bulbaholic and Linda235. I tried growing mint in a pot on my kitchen windowsill but it went the same way as yours. I've now re-potted it and put it outside where it's much happier.

If that's been in the same pot for a year, its time to do something with it, as its a small pot - turn it out, split it in half, replant half in the same pot, pot the other half up (if you like) and stand that one outside. Mint, over time in a pot, dies out in the middle, and should be turned out periodically and this procedure carried out.

Thank you all, outside it will go.
P