If you want to send a letter to your bank requesting a copy of your account statement, you could probably follow a template like this:
Re: Request for copy of statement of account for account number ______(enter your account number)
Dear ____(address to your bank manager),
I am writing to request a copy of an account statement for the above mentioned account held at your branch. The time period I would like this statement to cover is from ______ to ______.
I understand in order to carry out this action you may need to contact me to authorize my account. Please do not hesitate to contact me using the following details:
Thank you for your co-operation in this matter and I look forward to hearing from you soon.
A bank manager or official is unlikely to send out a bank statement without having authorized your identity first of all. This is to help prevent crimes such as identity theft and fraud. As you may need to pass a security screening before this action is processed, it may simply be easier for you to call into your branch and ask for the action to be carried out in person. Alternatively, if you have internet or telephone banking, you may be able to get in touch with your bank to request a copy of a statement.
Some banks with an online banking facility may store statements from up to six months ago online. There may be a chance you have to pay a fee to access these details but check with your bank if you are unsure of how to proceed.