my folder option disappear!!!

my folder option in the tools option disappear!!!
i was told that my pc was infected by brontok and i can’t search anything with avast.
how to make my folder option reappear?

What folder option in what tools menu do you mean?
What OS do you have?
Any other problems?
What other security (related) software do you have installed?
Who or what told you that the system was infected?
What have you done/tried to clean the system?

The folder option i menu bar.
make the hidden files appear.
i use avast full scan but nothing detected.
i ask in other forum,and some people told me that i was infected by brontok.

ok, first lets make sure your system is really clean.
Click on the link in my signature and follow the instructions on that page.
If you want to select another language, click on one of the flags.

after i used CleacX-II,the brontok was deleted.
i just wonder avast can’t detect and delete it?