What can I do about a torn tendon in my foot?

2 things. It will usually need immobilization or surgery.
See a doctor. How do you know you tore it? If you did didn't the doctor offer a treatment. Usually, a torn tendon is either primarily fixed by suturing it together or wrapping in a special graft like material. (there are other repair methods.) some tendons a doctor may not repair i.E tibialis anterior. It all depends on your age, activity level, length of time that has passed. But you should see a podiatrist.