can't access

hello, i'm using elgg 1.7 and the database was very very big with so many system_log_($now) tables, i deleted the old tables but before that for a weird reason i can't login to the system, i hope that deleting the old tables let me access to the website but still can't access, a few months ago i had the same problem but was solved checking and reparing all the database, i tried again but don't work

any help?

may i try to empty the table system_log ??