I have saved a Gimp pattern - .pat in the patterns folder - everything is saved right.

It does not show up in the patterns, help me.

I have done this right before on another computer but it's been a long time and now I am clueless.

If you had your Gimp open when you saved it, it won't show. shut down gimp and re-open it and see if it is there. or there is a little white curved arrow, click that and refresh.

Your patterns should go in your user folder.

did you put it in the right folder ?

you can check under:
edit -> preferences -> folder -> patterns

where your patterns are saved