IPhone won't update to 10.2.1( snapchat app not working)?

So every time I try to update my phone it says verifying update and then it says An error occurred, the worst part is it had to temporarily delete a few apps and then they said waiting in them. When I pressed on 3 or 4 of them they started looking like a regular downloaded app but my Snapchat app still says waiting 5 days later. (Today) how can I get it off waiting?

I repair iphones… Ok put it on charge and under general reset/ erase all content and settings / after restarts leave on charge until 60% or above… And power off. Now power on and set up as new phone, don't bother using your account details, put Wi-Fi password in and go to general, about and update… If all goes smoothly then reset all settings and sign into your account, you could always connect to itunes via pc / mac and update through that if not