What do you mean "claimed taxes"? That doesn't mean anything.
If you were employed as a salaried employee, your employer would have taken taxes (CPP and EI) off your pay automatically and remitted them to Canada Revenue Agency.
If you filed income taxes then Canada Revenue Agency will typically give you money back. (Most people overpay taxes and get money back when the figure out their deductions). When you file, you'd get a check back from Canada Revenue Agency (or they would direct deposit if you provided that information in your income tax returns). CRA would also send you a 'Notice of Assessment' which confirms you filed and shows the exact amount owed, paid, and returned -- which may not be the same as your return since CRA may have found mistakes, disallowed deductions, etc.
If you never filled... CRA will keep the money.
If you are self-employed (and earned more than $3,500) you are required by law to file income tax returns.
You presumably know when you last filed income taxes. This isn't something most people forget. They remember spending days filing out forms, getting RRSP amounts, getting T4s, etc. Most people would also have copies of their returns. If you filed through a tax preparation place, they would have copies and if you filed electronically your tax preparation software would have a copy. Finally, you would always have a copy of your notice of assessment sent to you by CRA. Most people remember these because if they don't get them, then CRA hasn't received their returns and they don't get hundreds or thousands of dollar back. In addition, most people keep their notice of assessments as proof so that CRA doesn't show up at their doors and arrest them.
And yes, you would have bank records showing when you deposited your income tax return cheque or direct deposit from CRA. Again, not something most people forget about. For most returns it is thousands of dollars.
If you are so bad with your paperwork that you can't remember filing a return last year, getting a cheque from CRA, getting a notice of assessment, etc. ... you can go online at the CRA web site and request a copy of any notice of assessment which have been sent to you. If you need copies of your actual income tax returns, you would have to visit a CRA service center with appropriate ID.