The answer to this depends on whether you closed your account yourself, or whether the bank did - and what the reasons for that were.
If you closed it yourself, then all you need to do is to write to your bank manager saying something like:
Dear Sir (or his or her name if you know it),
Re: Account number XXXX (Put your old account number in here).
I am writing to request that you re-open my above bank account which I closed on XXX (Put date here.) If this is not possible for any reason, I would be grateful if you would let me know what I need to do in order to open a new account, as soon as possible.
I look forward to hearing from you.
Yours faithfully (or sincerely, if you know the bank manager's name)
XXX
However, if the bank closed your account because they weren't happy with something to do with the way it was being run, you will need to tell them how your situation has changed from whatever was happening to you to cause you to have problems managing your money at that time, so that they can be reassured that you are now in a position to run your account in a way that they will be happy with.
If you didn't tell the bank what happened to lead you to have problems with your account at the time, then you should now explain (briefly) what those problems were and then tell the manager how your situation has changed since then.
The first rule of trying to deal with any financial problem is to communicate with the company as soon as possible, and to tell them the reasons why you are having difficulty. I know it's very tempting to ignore the problem and hope it will go away, but - if they know you are facing temporary difficulties - then they will often be in a better position to decide whether they can help you, by accepting reduced payments etcetera.
Hope this helps, and good luck!
If you closed it yourself, then all you need to do is to write to your bank manager saying something like:
Dear Sir (or his or her name if you know it),
Re: Account number XXXX (Put your old account number in here).
I am writing to request that you re-open my above bank account which I closed on XXX (Put date here.) If this is not possible for any reason, I would be grateful if you would let me know what I need to do in order to open a new account, as soon as possible.
I look forward to hearing from you.
Yours faithfully (or sincerely, if you know the bank manager's name)
XXX
However, if the bank closed your account because they weren't happy with something to do with the way it was being run, you will need to tell them how your situation has changed from whatever was happening to you to cause you to have problems managing your money at that time, so that they can be reassured that you are now in a position to run your account in a way that they will be happy with.
If you didn't tell the bank what happened to lead you to have problems with your account at the time, then you should now explain (briefly) what those problems were and then tell the manager how your situation has changed since then.
The first rule of trying to deal with any financial problem is to communicate with the company as soon as possible, and to tell them the reasons why you are having difficulty. I know it's very tempting to ignore the problem and hope it will go away, but - if they know you are facing temporary difficulties - then they will often be in a better position to decide whether they can help you, by accepting reduced payments etcetera.
Hope this helps, and good luck!