Disappearing Outlook Folders

Hi, I hope somebody can help me cause I have had no luck so far! I am running outlook 2003 and I have recently had a few problems. About 2 weeks ago one of my folders disappeared. I was sure if I had accidently deleted it or not but could not find it in the deleted items or anywhere, and the same problem has happened again today, and I know I didnt delet the folder or move it accidently this time.
Can anybody please tell me
A) why this happening and how can i stop it
b) can I recover the folders and how

I have tried recovery tools but none of them find the specific folders that are missing.
I would appreciate the help