Control Panel - reseller and owner issue [need help ASAP]

[oddyutza]

Starting today my reseller account doesn't work, also the domains accounts have the same issue

when i try to login it says : "Query was empty" but the link looks ok
cp.domain.tld/client/index.php
cp.domain.tld/reseller/index.php

the administrator account works perfectly. I also tried to switch accounts from administration, and i encounter the same problem. After a server restart is the same.

i ran out of ideas
Please help thanks in advance