help (no taskmgr,cmd,regedit and access denied)

So recently I upgraded from 7 to 10, the thing is its already crazy buggy when it first started.
so first Edge doesn't work... then after 1 hour, I gave up and restart the computer and reset my PC.
Afraid of losing my stuff, I choose to keep my files.

then good news Edge is working.

now... new problem discovered.
I'm new in windows 10.. so bear with me
I discovered..
1. Task manager doesn't work anymore (does work before reset)
2. I'm in admin local account, however C drive access is denied (but I guess that normal for W10)
3. that does not stop there. most programs (app) on C drive is also not accessible. like
taskmgr, cmd(admin), gpcedit.msc and somewhat others on system32.
4. when I tried to run them it says "windows cannot access C:\WINDOWS\system32\taskmgr.exe"
error code 0x800704b3
5. troubleshooting/diagnosis doesn't work it says "A problem is preventing the T.Shooter from starting"
error code 0x80070005

so I tried to search for solution most of them doesn't have exactly like mine.
cmd cannot run as administrator is one of the main thing I can't do most of the solution found online.

so yeah. keep in mind I'm signed in as administrator. just that it is not seem to be working as one.

please help.
thanks in advance,

hey thanks for the reply.
yes I've done that too.
the thing is I can create an account with Microsoft account(only) or phone number(I guess)
but that is not working either. maybe it has something to do with this "Network Error- Windows cannot access C:\Windows\system32\*.exe"
which surprisingly blocking me from installing certain software as well as long as it need administrator permission and have location on the C: drive related. like on desktop of download folder.
but just for fun let me try that another account with admin account type one more time.. brb

Edit: nope still the same message "Windows cannot access ...." 0x800704b3

I did something else I took ownership of drive C: ... crazy but at least that works. with permission to Trustedinstaller, Users, administrators and authentication users all together... but with different set of permission to them. so far I still haven't see the problem after I took that ownership.... but store app got worst. (from cannot login to cannot open at all, just flashes) then photo app cannot run, don't really matter because there is a lot other software for that. better even. so yeah I mark this as solve. thank you very much.

Hahaha, It actually did. well turns out that there are more apps that doesn't work.... however I then found more solution... I tried the Tweaking.com windows repair... honestly I first think it's not gonna help much... but what do I got to lose more than I already have...

right now I manage to open, login and use properly for most of the preinstall app.
to list it, the one that I still can't get to work is the Money App, News App, Sports, Weather, Get Skype, Xbox and Groove Music...
the Others are working... some work but like crap (example Alarm&Clock - the world clock is just 2 shade of gray with red/orange dots saying time for places that I search for....)

owh but I might want to know how to fix the missing Icons for some app....
let me list that.

Photos App
Calendar
Get Started
Get Office
Groove Music
Money
Movie&TV
News
Sports
One Note
Voice Recorder
Weather
Xbox

should I make a new post for this?

I second the Repair in place. Started using it at work were we fix 30 PC`s a week. Its a godsend. Its worked on 90% of the Win 10
Installs that run amok. Saves Data, Apps, Rebuilds the Store/SxS and does all the upgrades in one pass. And its neophyte friendly.