Can i use any brand of lens for my nikon n75?

Or does it just have to be a nikon lens?

You can use Nikon lenses.

or Sigma or Tamron lenses with a Nikon mount.

What deep blue said, if your willing to operate manually you can use other brands but will need an adaptor

YES, provided it has the correct adapter. I have a Vivatar 70-210 macro-zoom lens bought in Japan in the 70's which works perfectly with my Nikon F2 (vintage 1968) and my Nikon F (vintage 1955). The thing is, it FITS and couples the aperture setting. As long as it couples correctly, ANY lens will do… BUT! The BEST lens is a genuine Nikon lens!