There are two features in Windows 10 which will allow you to fix many problems with your computer:-

 

1.System Restore - this allows you to restore your computer back to a previous date when all was working okay - see here for instructions

 

2.Reset this PC - this feature allows you to reset your computer back to factory defaults and automatically reinstall Windows - you can choose to keep your personal files or remove everything - instructions below

 

 

 

 

 

 

To access the Reset this PC option click Start > Settings > Update & Security > Recovery and click Get started under the Reset this PC heading

 

 

You will then see the following screen where you can choose to Keep my files or Remove everything

 

 

Next you will be asked if you wish to re-install Windows using the files available locally on the computer, or if you wish to download the files required from the cloud.  The benefit of choosing Cloud download is that it will download and re-install using the latest available version of Windows 10, whereas the files already stored on your computer could be an older version meaning it would still need to download lots of updates once re-installed.

 

As long as you have a good speed internet connection I recommend choosing Cloud download

 

 

 

Your computer will then restart and perform the chosen operation - this process can take some time and the screen may go blank for long periods - wait patiently and DO NOT turn off your computer

 

After the reset is complete a file will be placed on your desktop titled "Removed Applications", if you double click on this file it will show you a list of what programs were removed from your computer during the refresh, so you know what needs reinstalling