Where ever have you been? I've been looking for you everywhere!

Who ever told you I'd lend you the money? I've no money at all!

ever here is not necessary in the sentence but is added to emphasize the speaker's surprise/astonishment/anger/irritation/dismay. It has the same meaning as on earth/in the world.

Such sentences are always spoken emphatically and the intonation will convey the speaker's emotion:

Why ever did you wash it in boiling water? (dismay)

Who ever are you? (The other person is presumably an intruder.)

Who ever left the door open? (What stupid person left it open?)

Where ever have you put my briefcase? (I can't find it anywhere.)

What ever are you doing in my car? (astonishment/annoyance)

When ever did you leave home? (You must have left very early.)

How ever did he escape unhurt? (The car was a complete wreck.)

Note also why ever not? and what ever for?:

You mustn't wear anything green. ~ Why ever not? (I can't understand the reason for this prohibition.)

Bring a knife to class tomorrow. ~ What ever for? (I can't understand what I need a knife for.)