NI contributions missing

Hello I hope everyone is well I have checked my National Insurance record on the Government Gateway and this says I have not paid any NI for the years 2012/13 and 2013/14. I was in full time employment at the time and my payslips show NI contributions. I have most of my payslips from this period to prove this. How would I go about proving this with HMRC and fixing this error? I can post the payslips if needed. Also please note my employer from this time no longer exists, so I can't contact them asking for any info. Thank you so much

Hi Focus,
I would advise you to firstly contact the National insurance helpline on the details further below. Once security has been completed, they can review those tax years as they are now.
Based on your comments about the tax years 2012/13 and 2013/14 if there are any issues, we may be able to resolve them due to your old payslips. 
The helpline may ask you to send in copies of your P60’s/P45’s or the final payslip from your employer/s in both tax years as your evidence of when you were an employee, or they explain the reasons why the tax year is classed as a non-qualifying.
Telephone Number - 0300 200 3500
Overseas - +44 19 1203 7010
Fax - 0845 915 7800
Overseas Fax - +44 19 1225 7800
You can chat to an advisor online through your personal tax account also - personal tax account,
Address
PT Operations Northeast England
HM Revenue and Customs,
BX9 1AN
Open Monday to Friday: 8am to 6pm
Closed on Saturdays, Sundays, and Bank Holidays.
National Insurance: general enquiries
Thank you.

Thanks so much for your help, I will contact the helpline.