Windows 10 Pro updates Stuck

The c: drive of my new windows 10 pro PC had only 40 GB space which was causing the PC to run dead slow, so to increase the space i deleted the recovery partitions which were showing immediately after the C: in disk management, and added those (with some more space from D:) to make C: of 200GB.

After that, PC is running super fast, but the following issues have cropped:

1. Windows updates are stuck. Though it shows downloading updates, it doesn't go beyond 0% and fails with an error

First it shows: Downloading 2020-09 Cumulative Update for Windows 10 Version 2004 for x64-based Systems (KB4571756)

Then after few seconds it has an Error Showing: Your device is missing important security and quality fixes.

There were problems downloading some updates, but we'll try again later. If you keep seeing this, try searching the web or contacting support for help. This error code might help: (0x80070002)

2. "Pause updates for 7 days" is disabled, and "Pause Until" has also got disabled completely.

and

3. Unable to install programs like Microsoft SyncToy, as it need .NET framework. When trying to install it, it throws error that some other version is already installed.

4. on startup, PC directly shows login screen of the only available userid. Earlier, there was a second login id to choose for recovery.

Please can someone provide inputs on how to get these things fixed? Resume win updates and pause feature, and enable installation of programs.

Many thanks.