I think you might have it wrong: "contact your bank" (not back) means to call your bank and talk to them about your accounts - if there are problems, that sort of thing.

A bank, in case you do not know, is a place where you can store and retrieve your money, as well as make investments.

A nerd and a geek are basically the same thing: someone who spends a lot of time in front of their computer, someone who doesn't have many friends, someone who is "different". It is not necessarily a bad thing to be considered a geek or a nerd.