This page lists out lost media (primarily marketing material) from the handheld Sims game. There is likely more lost content related to these games than these. These are just the ones I'm aware of.

Urbz Website Content

The official Urbz website (on the wayback machine) existed from 2004 to, at the latest, 2013 (EA cancelled their trademark with the term 'The Urbz' in 2013). It was a flash-based website that contained various information on the world and characters (among other things) from all versions of The Urbz: Sims in the City (admittedly, for the console version of The Urbz, more of the game world's lore was held there than the actual game). Possibly due to a lack of care, or due to the fact that the website was mostly flash files, much of the website was lost to time.

Many of the character profiles for the console version of The Urbz were archived, as screenshots of them can be found on The Sims Wiki. From looking at other screenshots of the profiles, it becomes apparent that they had been archived in a video recording. (I have never seen this video.)

The closest to those character profiles that have been found are two psuedo-character profiles from an old IGN video from about a month before the game's release. Some news reports at the time also mention the character profiles for the GBA characters being added to the website, but I've never actually seen any of the profiles.

It's not much (especially given how much we actually get to learn about the characters in The Urbz for GBA compared to console version), but it would've been nice to have!

The file name that contained this was named "peeps_gba.swf" (and maybe it referenced a few other .swf files). Its first an only archive on the wayback machine was in 2012, which, when looked at, only brings and potential viewer to the 404 page for The Sims 3.

There had also been blog posts by the writer of the game, Darby McDevitt, as the in-universe protagonist. A small snippet of this was preserved at The Sims Zone:

...Now this is an interesting spot to be in: dumped head-first into the Bayou's boggy waters. This is possibly the worst I've seen or smelled in years and, gee whiz, I stink. Ah, but I'm not hurt. That's a relief, of course. My situation could have been worse, I could have been snapped up by a gator. Or been thrown into the lion's den at the carnival in Glasstown.

Sims 2 for DS Guide

Not nearly as extensive, but, as seen in the Sims 2 GBA Guide, there had been official guides released for The Sims 2 for Gameboy Advance and Nintendo DS. This file was named "NDS_walkthrough.pdf" on the old Sims 2 website (also defunct). It still exists on the Wayback Machine, but it is corrupted and will fail to download every time.