Why I lost my points?

http://boincstats.com/stats/boinc_user_graph.php?pr=bo&id=3833b1d7c765e3c72d4a98492fcade11

Total number of points displayed in the client programs is much greater.

You have a split cpid.
The one you mentioned and 6755be1a2005cf7d429f851e80676886 for the projects Cosmology@Home and MilkyWay@home.
Probably you changed your e-mail on some projects recently.
The e-mail addresses should be the same at all projects (and BAM!), because the CPID is created from the e-mail address and is unique for every BOINC-user.

I changed nothing for two weeks. Until yesterday, everything was OK, what should I do now?

On 04 Aug 2010 you created an account at Seti@Home, but crunched no tasks until yesterday. (Seti@Home was unreachable for longer periods). There you have the other CPID (6755be1a2005cf7d429f851e80676886) too.
Did you used there the same e-mail address? If so, just wait a few days. Probably it will sort out automatically then.

Now I'm not sure anything
I have tried to use the same e-mail address everywhere. I hope that everything will be as it was earlier.
Thanks for the information