This question already has an answer here:
I've refreshed the page after some time on stackoverflow and all my reputation is reset. I saw a "-4600" notification and I was back to 100 or something (I was around 4600 before).
Also the username and real names were different (something like user984398). The only thing I remember doing was I changed my real name.
I can see all my answers though and still have my badges. And the log in here: https://stackoverflow.com/reputation looks fine.
My profile: https://stackoverflow.com/users/1242778/agis