If there are important folders, files, documents, presentations, etc. that you need to access without an Internet Connection, you need to make sure (while connected to the Internet) that you make them "Available offline"
1. Navigate to your Google Drive, select a folder or file, Press and hold the Control key while you click that folder or file and release.
2. With the menu that appears, look for Offline access and then select Available offline. This will take some time to sync your files to your local harddrive, depending on how many files and folders you are making accessible offline. Do not select all of your Google Drive files, because it may fill up your entire local hard drive.