Backup files...
So, I came across a problem recently. Where I had to fix the game with a reinstall. At first, I didn't pay that much attention, but I wish I had, mainly because of how Hammer worked for CS: GO. I lost my Hammer 2 map projects because of it. So, thinking ahead, I wish to pinpoint this. Once you need re-installing the game, follow these steps and You should be good with Hammer content.
I like to record and publish my mapping process, as much, as I can, so here you can see the building process of the lost map file... - Lost map file progress...
You can watch a video instead also, - YouTube tutorial
