Download the 2nd, 3rd and 7th drivers in this list. (Use any internet-connected computer, such as the one you used to post your question)
http://www.ralinktech.com/support.php
(The one you want should be among them. It won't do any harm to install all three).
Then, using removable media (such as a CD-R, DVD-R or media stick), copy the files onto your PC and double-click on each of them in turn, to run their installation programs .
Chris