She stopped watching movies then she watched a movie by mistake, and she is asking how she can stop watching them
Question

                I vowed that I would not watch movies, but I did not stipulate any particular type of movies. One year later I watched the movie that was not bad or indecent.

My question is: how can I stop committing this sin?.
Praise be to Allah.
    The ways in which you can give up watching movies: you can 
    achieve that by means of several things that were mentioned by the scholars 
    and educators, such as the following: 

    1.Finding out about the shar‘i 
    ruling, which has been discussed previously in many answers.

    2.Bearing in mind that Allah, may 
    He be exalted, is always watching and that He knows what is secret and is 
    even more hidden. One of the early generation was asked about what they did 
    that help them to lower their gaze and refrain from looking at haraam 
    things. He said: By knowing that Allah sees you more quickly than you see 
    what you are looking at.

    3.Righteous friends who will 
    remind you if you forget and alert you if you are heedless. They are close 
    friends who love one another for the sake of Allah and you are brought 
    together in obedience to Allah, may He be exalted. Allah says 
    (interpretation of the meaning): “Friends on 
    that Day will be foes one to another, save those who kept their duty (to 
    Allah)” [al-Zukhruf 43:67]. That is the good companion whom the 
    Prophet (blessings and peace of Allah be upon him) likened to the bearer of 
    musk. It was narrated that Abu Moosa al-Ash‘ari (may Allah be pleased with 
    him) said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    said: “The likeness of a good companion and a bad companion is that of one 
    who carries musk and one who works the bellows. With the carrier of musk, 
    either he will give you some or you will buy some from him, or you will 
    notice a good smell from him; as for the one who works the bellows, either 
    he will burn your clothes or you will notice a bad smell from him.”

    4.Keeping yourself busy with 
    things will benefit you in religious and worldly terms. You should have a 
    daily wird that you recite; memorize the Book of Allah; study some books by 
    the scholars or listen to them, and busy yourself with things that are 
    beneficial and serve the people and society.

    5.Marriage, which is what the 
    Prophet (blessings and peace of Allah be upon him) recommended to help lower 
    their gaze and guard chastity, as he said: “O young men, whoever among you 
    can afford it, let him get married, for it is more effective in lowering the 
    gaze and guarding one’s chastity. And whoever cannot afford it, let him 
    fast, for it will be a shield for him.” 
    Narrated by al-Bukhaari (4779) and Muslim (1400).

    6.Always asking Allah to help 
    you, guide you and purify your hearing and sight. The best thing that a 
    person can do to rid himself of evil inclinations after taking the proper 
    measures is to turn to his Lord and ask Him to help him with that, to make 
    things easy for him and to purify his physical faculties.

    We ask Allah to enable you to do that which He loves and that 
    pleases Him. 

    And Allah knows best.