I also lost my RDB about a month ago. However, the problem was easily fixed. I used SFSSalv which can be found in the sfs_beta archive on Aminet. This little proggy gave me all the info I needed to put into HDToolbox. After I saved my settings, every partition was back. All I needed to type in was the start and end cylinder of each partition. Try it out, you might be lucky :-)
Btw. what filesystem did you use on the harddrive? If you remember which you had, it might help you to place this filesystem on your Workbench disk as well.