Download your version of the Windows 7 ISO, burn it on dvd or USB and use it to run the Startup Repair, or if necessary run a Windows 7 Repair installation, or a format and clean installation. Don't know how compatible the USB installer creation woud be from Android though. An DVD burn may be a simple ISO burn with a burner connected via USB adapter to the Android tablet. If necessary to activate your Windows use your product key.
Official Windows 7 SP1 ISO Image Downloads (These ISOs need a valid product key to Acivate)
http://www.mydigitallife.info/official-windows-7-sp1-iso-from-digital-river/
http://www.w7forums.com/threads/official-windows-7-sp1-iso-image-downloads.12325/