Here is an explanation letter why you are unable to provide a certificate of employment from a past employer or company
Dear Sir,
In line with your application requirements, I am unable to provide a certificate of employment for my work duration for Green Fields LLC which I was employed full-time ten years ago. The company has closed back in 2008 due to the economic recession and all administrative employees handling employee records have moved on to other companies. I have tried my best to contact any legal representative of the company, but to no avail.
What I can do is provide an attestation letter from a former supervisor who had worked at Green Fields LLC during the time I was employed. I hope this document would suffice.
Hoping for your consideration.
Thank you very much,
Lea Claire Woodrow