Depends on what you mean by losing EVERYTHING. I suppose if I lost everything, including my memory, my personality, myself.. Than I wouldn't do much of anything except probably sit and be one with the universe. If I still had my personality and the ability to remember basic maths and speech at least, I think I'd have a pretty epic adventure, because it would be a second chance for me. I could be whatever I wanted. In that case I would:

• Become a detective. Maybe just so that I could find out about my past. From the perspective of having a memory, I wouldn't want to remember most of it, however, if I had no recollection, I suppose I would wish to know.
• Make new friends. Any friends I accumulated would probably think I'm crazy, so naturally, they would be very good friends.
• I would go on an epic road trip in a stolen school bus, because hell, I have no expectations to live up to. And honestly, you probably couldn't stop me if I really wanted to do it.
• I would do everything I ever wanted to do, because I would be free of everything that once constrained me. At least, I feel like that would be the case.

If I lost only my material posessions. I suppose that would simply count as a new start as well. Life would probably suck. A lot. For a bit. But if that was the case I could:

• Become a minimalist.
• Redecorate.
• Move. Obviously.
• Mourn only the loss of my great-grandmother's ring, my notebooks, and my stuffed animal named Diddl.

Because seriously. I am off the mind that loss is actually a rejuvenating thing, a cleansing, in an odd way. However tough it might be at first. The only exception I think would be losing a person. I don't think I could bear losing people unless I also lost my memory and had no recollection of them.