How does MySQL resolve schema information? I’ve used MySQL on windows7.

Recently my machine was infected by a virus.

After that SHOW TABLES and SHOW DATABASES statements don’t show any tables and databases but I can see data from tables which I’ve created with SELECT statement.

In addition mysqldump doesn’t work. It makes dump file but there is no data.

mysqldump can’t resolve database and table names.

I think SHOW statements and mysqldump use information_schema table.

Then my question is how does MySQL resolve schema information when it create information_schema table?

There must be some resource that information_schema refer to.

I believe the resource was destroyed by the virus,and I want to fix it.
I found a cause.
All folders under the data directory were hidden attribute.
I changed them then I can see tables and dump data.