Vikshar

If this is a reinstall, go to your .minecraft folder and delete all the .json files relating to the launcher. Hope this helps!

When you reinstall Minecraft and relaunch the launcher, No versions will show up. Navigate to your .minecraft folder and delete all the .json files you see there relating to the launcher (launcher profiles, etc.) Now relaunch the launcher and sign in again, and you versions will be there again!