During a very stressful period in my life, i got bell's palsy. could the stress be the cause of it?

Yes: Stress can be a cause of bell's palsy usually by reactivating a latent virus. Check with your primary care physician for more information.

Bell's Palsy: Causes of damage to facial nerve are usually unknown, but some are herpes zoster, lyme disease, hiv, sarcoidosis, & middle ear infection.

Unlikely, but: Bell's palsy seems usually caused by herpes viruses, both simplex and zoster. Also, can be seen in sarcoidosis, and lyme disease. I do think that stress can affect the immune system, and indirectly, you became more susceptible to infectious process. However, stress directly is not the cause, otherwise. Might propose a few tests to make sure no additional process which is obscure.

Possible: There is no definative causes for bell's palsy, but stress has been cited in much of the medical literature as a probable cause.