Hi Grokh,
Thank you for posting on forum.
I understand that since you update your Nokia Lumia 920 to 8.1 version you have an issue with download or update apps in the store. You are getting error code: 80073cf6.
First of all, I would check if automatically settings for time and data are turn off, set them manually. Also, make sure that option: find my phone, localization; backup are turn on.
What is more, please double check that you have right region with language on phone after soft reset and try to use other Wi-Fi.
If issue still persists, I would perform hard reset. Put your phone to factory settings and set it up again with your Microsoft account.
Please do not forget backup your data. More info you can find here:
http://www.windowsphone.com/en-us/how-to/wp8/basics/back-up-my-stuff
http://www.windowsphone.com/en-us/how-to/wp8/basics/reset-my-phone
Thanks for your contribution to the forums!
Kind Regards,
Michal TR
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