normally you can activate the trial version without re-installing.
Do you activate or register button ?
if not you can enter the serial number in the program (help->about)
there is a post about how to do this (meant for netbook using Keyboard, should work for any pc)
http://forums.autodesk.com/t5/AutoCAD-Freestyle/Activating-Freestyle-on-a-Netbook/m-p/2681221
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Hashim Mundol
Autodesk Product Support
Autodesk, Inc.