Acer aspire one d 250 reformat

Hello,

i have acer aspire one d250 netbook, and i think it has many viruses couse it is workin so slowly. i would like to reformat the system. but i dont know how i can do it, couse of there is no cd drive, and i dont have the external cd driver.

If i do the Alt + F10 is it work? and how can i reinstall the windows system to my netbook? Could you pls clarify me?

Thnx a lot