Hi @Anonymous,
With a reinstall most of the time it will work. But there is an easier option;
Let your classmates put there total families map on a USB drive or let them send you the files with wetransfer.
Than you can change your map with theirs in the same folder. You can find your folder in your (in windows) hided ProgramData folder.
*/ProgramData/Autodesk/RVT2017/Libraries/"Your Country"/
There you can put all the families and it will solve your problem