Do you have to submit a copy of your dissertation to check your ability?
If you no longer have the copy, can you be assessed in other ways?

I've never heard of this actually. Does the course say it is required for admissions?

No. It did not say.
Actually my application was declined because I was not able to provide the copy of my dissertation. I was requested to submit this after I made my initial application. The thing is my bachelor's degree was from more than 10 years ago and at that time we were using USB sticks and I no longer have the copy with me. I contacted the university of my bachelor's degree but they do not keep the copy on their system.

The reason why they needed it was to check my writing ability. So I also proposed to write an essay if they give me a question or topic to write about but I did not get a reply for that and I was just informed that my application was not successful.

That's unfortunate. Could you try contacting them until you get a satisfactory response?

Thank you for your reply. Yes but I do not know what to say.
If you do not mind me asking how would you approach it.

I have submitted my academic transcript as it was required for admission and I have a 2:1 for my dissertation.
It is from a renowned, top 50 university in the world as well.
I still do not understand why they would still want to see my actual work.

I guess it might be because your degree was quite a few years ago. How about something like:

Dear Admissions Team

Thank you for your recent email (below). EXPLAIN ABOUT HOW YOU APPLIED AND THE RESPONSE YOU GOT. ASK IF YOU COULD SUBMIT A SAMPLE OF YOUR WRITING INSTEAD.

Thanks for your time and I look forward to hearing from you.

Kind regards

@Tudor_Queen
Thanks. In fact I proposed to write an essay if they could give me a topic or question to write about but instead of receiving an answer to my question I was just informed that I was not successful. I have been away from the academia since 2007 so I do not have any written work that I can submit straight away.

Sounds a good idea. Hope they will agree. I can't see why they shouldn't agree. But if they don't then they should at least provide a reason.

Maybe if you don't hear back from the email in a week you could try calling? They might be out of office though due to the pandemic.

Good luck.

This might be crazy but if this issue keeps occurring you could start a blog. A blog might be enough to show that you can write small essays about relevant topics.

@rewt thank you. It is a good idea. I even had to submit English proficiency test result, which also proves that my writing ability is OK.