I have only one testicle. I want to know if there's a way to get the other testicle to descend without having to go to the doctors to get it done surgically, preferably if I could do it at home.
There are two possibilities: either you have only one testicle or you have two, but one did not descend as it should have when you were born. Even with one testicle you have more than enough capacity to make up for the missing testicle. You develop normally and be fertile as an adult.
You need to talk to your doctor about this, but typically an undescended testicle has to be treated when a boy is less than 18 months old. If you wait until you're a teenager the testicle will not develop properly or may no longer be present.
The primary concern about an undescended testicle is testicular cancer. "An undescended testicle is more likely to develop cancer, even if it is brought into the scrotum with surgery. Cancer is also more likely in the other testicle" ["Undescended Testicle," MedlinePlus]. Your doctor will keep watch for this during your regular checkups. It isn't something you should worry about, but it is something to be aware of. You will need to learn how to check for yourself for cancer. When you shower, lightly hold your scrotum and gently feel the outer surface of the testicles. The testicles should feel smooth and oval or egg-shaped. If there are any changes, see your doctor, such as a hard lump, then you need to see your doctor about it. Usually, once you get past your twenties, the odds of getting testicular cancer drops.