Hi Manish,
Unfortunately, no refund of National Insurance contributions is available to you. As the contributions were correctly paid, then they must remain recorded on your UK National Insurance account. They may, however, help with your US Pension and you should let the US Pension Office know that you worked in the UK when you make your claim to pension.
If you lived in the UK for 3 years or more you may wish to consider paying voluntary National Insurance contributions to improve your UK Pension. Details are given in our leaflet NI38 ‘Social Security Abroad’ which is available here:
Social Security abroad: NI38
Thank you.