Check if there is enough space on hosting.
not space problem
from cs-cart support:
This error means that the cscart_sessions table has been corrupted and needs to be repaired.
Please note that a PHP script like CS-Cart cannot crash a MySQL database table. Usually, MyISAM tables can get corrupted after a system failure. You can contact your server administrator to resolve this issue or execute the following SQL query (for example via phpMyAdmin):
REPAIR TABLE cscart_sessions
but we not have the ability to fix, we don't have cpanel and all companies are closed to support,
seems an ecommerce not have support on holidays, a bit incredible
I bought some addons from your company, can you support to solve on pay?
Contact your host asap. A good host will get back to you within minutes, 24/7.