Film on Nikon not showing up?

Okay, so I have a Nikon FE, and I went through 4 rolls of film recently. I got them developed today and at least half of my pictures did not show up on the negatives or anything. Also they were all upsidown. I'm kinda new at all this so does the upsidown thing mean the lens is on wrong? Also, Why didn't my pictures show up?

Added (1). Also, for some odd reason, most of the pictures that didn't show were the ones I took outside?

The problem is that you don't understand how to adjust shutter speed and aperture properly to create a proper exposure. Film cameras are not like point and shoot digital cameras… You can't just start clicking away and expect the photos to turn out right. You need to sign up for a photography class.

By the way, there's no way to put a lens on upside down.

Have you set camera to the speed of film you are using? I don't see how you can miss setting shutter speed to 1/125 second or a bit faster outdoors. The ones that didn't show up on the negatives---was film actually advancing? Was crank knob going around after each shot?
I once owned the fe2, it had an A for auto. Shoot 1/2 your shots on auto, if they come out, it's you. Then ya know ya gotta learn the basics of photography.

I can't figure out how a picture is upside down, unless the developer may have made a mistake in printing. It's more of left and right sides switching, or mirroring. This happens a lot lately with fewer and fewer labs knowing how to develop film properly.

Next time, take a picture of some huge words like the Hollywood letters. That should convince the developer he's doing it wrong. Better yet, go to another film lab. The lens has nothing to do with it. It's not your fault.

As for the pictures not showing up, its just wrong exposure. Maybe your camera's lightmeter is not working properly. You might find this page helpful.

It might also help if you had the FE's user's manual. Try searching at http://www.butkus.org for one.

When a image is recorded on film it's up side down, as for the other I would say not enough light getting to the film.