My question is how to get over your past? Please provide a few references from Gurbani.

Very good question Harvsingh Ji. First we need to know our past and then how to get over it.
Whatever we learn throughout our life becomes our Purable Karam. A child told by mother not to go in dark because there are ghosts there, develops fear of darkness and belief in the presence of ghosts. A child witness mother and siblings beaten by father develops fear of authority figure and might get rebellious as well. A child participating in religious activities becomes religious person in later life. These become our Purable Karam. Guru says:

ਦਿਨੁ ਰਾਤਿ ਕਮਾਇਅੜੋ ਸੋ ਆਇਓ ਮਾਥੈ ॥ ਜਿਸੁ ਪਾਸਿ ਲੁਕਾਇਦੜੋ ਸੋ ਵੇਖੀ ਸਾਥੈ ॥ ਸੰਗਿ ਦੇਖੈ ਕਰਣਹਾਰਾ ਕਾਇ ਪਾਪੁ ਕਮਾਈਐ ॥ AGGS 461
Din Raat Kamayarro So Ayou Mathai || Jis Pas Lukaeidharro So Vekhi Sathai || Sang Dekhai Karanehara Kae Paap Kamaiai ||
ਸੁਕ੍ਰਿਤੁ ਕੀਜੈ ਨਾਮੁ ਲੀਜੈ ਨਰਕਿ ਮੂਲਿ ਨ ਜਾਈਐ ॥ ਆਠ ਪਹਰ ਹਰਿ ਨਾਮੁ ਸਿਮਰਹੁ ਚਲੈ ਤੇਰੈ ਸਾਥੇ ॥ ਭਜੁ ਸਾਧਸੰਗਤਿ ਸਦਾ ਨਾਨਕ ਮਿਟਹਿ ਦੋਖ ਕਮਾਤੇ ॥੧॥
Sukirat Kijai Naam Lijai Narak Mul N Jaiai || Ath Pehr Har Naam Simarhu Chalai Terai Sathe||Bhaj Sadhsangat Sda Nanak Miteh Dokh Kmate ||
The actions we perform day and night will influence us in our later life. So do good deeds and remember God all the time in the company of good people. These become our Purable Karam.

Can we change our Purable Karam? Guru says yes. Among all the countless creations only humans have the power of choice.
ਸਤਿਗੁਰੁ ਧਰਤੀ ਧਰਮ ਹੈ ਤਿਸੁ ਵਿਚਿ ਜੇਹਾ ਕੋ ਬੀਜੇ ਤੇਹਾ ਫਲੁ ਪਾਏ ॥ ਗੁਰਸਿਖੀ ਅੰਮ੍ਰਿਤੁ ਬੀਜਿਆ ਤਿਨ ਅੰਮ੍ਰਿਤ ਫਲੁ ਹਰਿ ਪਾਏ ॥ AGGS 302
Satgur Dharati Dharam Hai Tis Vich Jeha Ko Bije Teha Fal Pae || Gursikhi Amrit Beejia Tin Amrit Fal Har Pae
ਓਨਾ ਹਲਤਿ ਪਲਤਿ ਮੁਖ ਉਜਲੇ ਓਇ ਹਰਿ ਦਰਗਹ ਸਚੀ ਪੈਨਾਏ ॥ ਇਕਨ੍ਹ੍ਹਾ ਅੰਦਰਿ ਖੋਟੁ ਨਿਤ ਖੋਟੁ ਕਮਾਵਹਿ ਓਹੁ ਜੇਹਾ ਬੀਜੇ ਤੇਹਾ ਫਲੁ ਖਾਏ ॥
Ona Halat Palat Mukh Ojale Oye Har Darageh Sachi Painae || Ekanha Andar Khott Nit Khott Kamaveh Oh Jeha Beeje Teha Fal Khae |
True Guru is the field of Dharma; as one plants the seeds there, so are the fruits obtained. Those who plant seeds of good deeds, get ambrosial fruits (Everlasting Peace). Those plant seeds of cruelty get fruit of misery and sorrow. That means humans can obtain knowledge and change their Karam. That’s why Guru emphasized the company of good people. ਕਰਿ ਸਾਧਸੰਗਤਿ ਸਿਮਰੁ ਮਾਧੋ ਹੋਹਿ ਪਤਿਤ ਪੁਨੀਤ ॥ Kar Sadhsangat Simar Madho Hohi Patit Puneet || AGGS 631