Unable to start most programs & services on Windows 10

Since yesterday I am facing an issue on my computer, that occured after I needed to force reboot because of a graphic card crash.

When starting up my session, the sound service is not started, and my antivirus (Avast) is not starting as well. I am not able to start most of the programs (exe files, msi installations, and so on). Even some Windows 10 native programs (such as Add / Remove a program) won't show up. Some basic programs and others such as Chrome (?) are working fine.

When I try to start the Audio service manually, I get the message "Access denied". Moreover there are a lot of events in the Windows event logger that show up "Access denied".

I already tried some solutions found on the Internet:

• Restore exe files associations -> everything is correctly set up
• Running sfc /scannow -> no error message
• Checking owner of C: drive -> Adminstrators group is set with "Full control" on it
• Trying to register some missing DLL files -> the registration end point is not found on those DLLs
• Trying to safe boot -> same behavior occurs
• Trying to create a new user account as Admin - I also activated the Administrator account to check- -> same behavior in the new session

I also tried to rollback to a restoration point, however it fails with error 0x80070005: on the Internet it is said that I have to disable / uninstall Avast first. But the problem is that I cannot run anything that could be able to do that: they won't start because of the first issue.

Some more details about my configuration:

• 500 GB SSD with about 50% of free space
• 16 GB RAM
• Windows 10 Pro

Do you have any ideas? Thanks!

First, if you have not yet done so, make a disk image in case something goes wrong with repairs. This can be run from external media using a third-party backup program, such as free Macrium Reflect which can create rescue media using WinPE.

Then, in SAFE mode, try using DISM to repair system files:

• Open a CMD prompt as Administrator: press Windows, type cmd, press CtrlShiftEnter and click Yes in the UAC dialog.
• Type (or copy & paste) DISM /Online /Cleanup-Image /ScanHealth in the CMD window. Press Enter and wait some minutes for the process to finish.
• If corruption was detected, enter DISM /Online /Cleanup-Image /RestoreHealth and press Enter... and wait even longer for repairs to complete.
• After DISM finishes, repeat SFC /scannow.

If that does not resolve the issue, you can download the latest Windows 10 ISO and perform repair, or even a complete reinstallation.

It is possible to use DISM to repair using the file boot.wim in the Windows.iso\sources\ folder, but my experience has been that running the ISO in repair mode has a better chance of success.