Gameplay won't move past a certain time
@CHUBSTERLOU5 As mentioned, you can copy over the content of your old Sims 4 folder to the new one, although it's best to leave behind cache files and other extraneous data. The households and builds you've saved to the in-game library are in the Tray folder, screenshots are in Screenshots, mods and custom content in Mods, etc.
For the affected save itself, you can manually recover an older save from before Winterfest. The relative sizes of the save files will show you which ones are affected. Here's how to recover a save (use the manual method):
https://sims4.crinrict.com/eng/2014/09/save-games/#wiederherstellen
If your backups are affected as well, there are mod-related solutions to try to fix your save. I can't post mod links here, but this page has the information you need:
