If you ever loose or have your wallet stolen, here is the two best link I've found for what to do:

Mercer Savings Bank: Lost - Stolen Wallet Help

They even give you a phone number to call the Social Security administration with to have your file flagged, which isn't on the Soc. Security's own website on stolen Social Security cards.

For concern over your social security number, whether or not your card is stolen or lost, this link has the best advice I found. See items #2 and #6:

Privacy Rights: FAQ on Social Security Numbers

I found these after searching the web for help last week when an important friend of mine had things stolen from her wallet. Though oddly, and thankfully, not the entire wallet was taken.