Use another computer and go to Acer's support site to download the driver for the network controllers, i.e. ethernet/wireless cards and put it on a flash drive.
Hey friend. Join the club. Acer appears to have loaded their hardware (i.e., computers) with files (in the system BIOS) that, if you make any changes to the manufacturer's (here, ACER) specifications--such as up or down grading your Operating System--the said files than trigger some application that acts to wipe out the drivers necessary to operate hardware contained within their (ACER!) computers. Myself and many other professional IT's (having permissions to access my computer via the internet) tracked this entire... scam! Sorry, I have no more apt word. This scam. It would appear that what they want once you purchase their (ACER) hardware/software is that you go only to them for anything you may want or need to do to your ACER computer.
Class action lawsuit rings beautifully to me. Look at all the blogs on the internet concerning this very issue. We are not alone and certainly have enough members to get a ruling certing class action.