Have I been hacked? All but one customer has disappeared from customer tab & weird keywords & emails

[starxox]

Hi

Just logged in and noticed that only 1 customer is showing, I had about 80 on the mailing list and quite a few more with accounts but not on mailing list. I can still see all my old orders, but only 1 customer on the customer tab - does anyone know what's going on? (EDIT - PLEASE SEE BELOW - I made a mistake here, but the other problems still stand)

Also recently I've had a few bounced emails that show that someone is sending random messages from the 'send to a friend' module, with random letters being typed. I've disabled the module but messages still seem to be getting sent.

Also, in the search engine keywords bit, this keyword odno-klasniki.ru/319750.html has apparently led people to my site 18 times this year, and its a sex site! I've asked my hosting company about this 3 times now and they are normally very good but seem to be ignoring me which is really weird.

Help! What's going on??

Thanks

Louisa

[EDIT] Just also noticed that all my backups seem to be gone as well, I still have them on my mac but they are not there to download from prestashop

[iMPORTANT EDIT] Ok just realised I have a filter on the customers which is why only one is showing,but when I try to get that filter off I get that annoying message 502 Bad Gateway. All the other problems still stand. thanks