Yeah, Kangaroo's right. All the old data is lost to Mahz, so you'll have to rely on your own searching to hopefully find something.

The Wayback Machine (archive.org) has a lot of snapshots of parts of the site from various dates. You could try browsing your way to a thread you posted in and hope it was from a date where you had your desired avatar and sig, then grab those.

Alternatively, you can search Google and hope they cached a thread/page you want. The best way to do it is to search 'site:roleplayerguild.com' (to make it only give results from RPG) followed by either an exact thread title or the crap shoot of trying various keyword combos if you don't remember the exact name. If a page comes up that you wanna check, don't click the hyperlink. Below it, the URL will be shown in green text; if there is an arrow off to the right of that, click it and press Cached to be brought to Google's cached version of the page.

Good luck with your retrieval efforts.