Is there a way to fix a crooked mouth?

It sounds like you may have Bell's Palsy, which is believed to due to a pathology involving the facial nerve.  It can permanent or temporary, but in over 90% of cases, it is temporary and self-limiting.  It is most commonly due to an inflammatory process that is putting pressure on the facial nerve.  This condition is often resolved by simply taking corticosteroids to reduce the inflammation and alleviate the pressure on the nerve.  It is important to see your primary care doctor or a cosmetic dentist to receive corticosteroids to limit this condition very soon, because prolonged pressure on any nerve can cause irreversible damage to the nerve and ultimate death of nerve tissue, which would leave you with permanent Bell's palsy.  Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMD

There actually is a
chance that this is neuromuscular. However, if it is not, you may want to
discuss treatment with an orthodontist that is teamed up with an oral surgeon.
Together, they could help determine what type of treatment is necessary to
manipulate anatomical bone structure so that your smile looks straighter.

You should consider seeing a neurologist.  This is a frequent sequelae of Bell's Palsy, but I'm not saying that's what you've got.  I'd start there.