YOU SAID:

i cant not belive that worked

INTO JAPANESE

それがうまくいったことが信じられない

BACK INTO ENGLISH

can't believe it worked

INTO JAPANESE

効果があったのが信じられない

BACK INTO ENGLISH

i can't believe it worked

INTO JAPANESE

それが効いたなんて信じられない

BACK INTO ENGLISH

i can't believe it worked