How many bank accounts do you hold? 2? 3? 4?
How about that one account that you opened while in college and haven't bothered to check again? Has it been two years since you withdrew from or deposited money in that account?
You may be surprised to find that you are not able to transact in that account anymore. This is because that account of yours is now designated as a dormant.
Fortunately, it's quite straightforward to get these accounts back in active state. This post covers dormant accounts in detail as well as lists steps to reactivate them...