I forgot my password lost all of my settings when I created a new one and now I think I remember my old password

I bought an iPhone and an iPad and I’ve never used Apple products so when I downloaded Firefox to use on these I had forgotten my password so I created a new one but I’ve lost all my bookmarks and stuff.

Well now I think I might remember my old password so how do I go about trying to get all my old stuff back because I’m I’m basically I’m an old fart and I can’t remember all of the websites that I had bookmarked