Some things I could point out for you:
[WARNING] Unable to load installedPacks from C:\Users\user\AppData\Roaming\.technic\installedPa cks because it
does not exist.
[WARNING] Unable to load users from C:\Users\user\AppData\Roaming\.technic\users.json because it
does not exist.
Looks like some parts of your .technic folder is missing. Or possibly, most of the directory?
Error Code 403 means that the resource you're trying to reach is forbidden for some reason (for example: You don't have the permission to access it) But this shouldn't affect the game itself, only the news feed on the launcher.
[STDERR] Caused by: java.lang.RuntimeException: java****.FileNotFoundException: C:\Users\user\AppData\Roaming\.technic\modpacks\te kkitmain\config\CodeChickenCore.cfg
Now this is just like what it seems, the error is caused by "CodeChickenCore.cfg" not being found for some reason. Probably the key reason to why your game is not working.
TL;DR/What you should do: Try reinstalling the pack. Or clean everything off the .technic folder and set up the launcher, install your modpacks, everything as usual. (
NOTE: Backup your saves, screenshots, anything you want to keep.)