Most of us have worked for many employers over the years. On average, a person moves jobs and indeed home every 7 years or so. It is no surprise that you may have forgotten whether you had a pension scheme with that job you had when you were 22 years old.
It may be that you did not even know you had a pension scheme.
It may be that your employer or your works pension lost contact with you because you have moved a number of times and did not tell them or did not know to tell them.
They may have been trying to trace you for a number of years but have not found you.
If you have moved abroad they probably have little chance of tracing you.
Just over 5 years ago, the Department for Work and Pensions launched a free pensions tracing service to help people track down old pensions.
If you have time on your hands during the coronavirus lockdown period, it may be useful to list out all your employers and either track them down and write to them or give details online to the pension tracing service who will do it all for you.