Given that this started 3-4 days ago I would suggest using Windows Restore to revert back to a time before the problem started. Two ways to do this.
The simplest way - if you can get the computer to boot to a normal running condition - is 'Start / Control Panel / Recovery / Open System Restore'. Here you will be offered a restore point. by default it is the latest. If this does NOT date from before the start of your problem, there is a button 'Other restore points' (or wording like that). This will bring up a list of all available restore points. Pick the latest one that dates from before the start of your problem then click 'Restore'. Let Wiindows do its thing, it may take up to 5 minutes, and things should be normal again.
The other way can be a little more complicated. You start by pressing the 'F8' key while the BIOS screen is showiing immediately after switch-on. This should take you to the 'Advanced boot options' screen which is black with white text. At the bottom of the screen you will see a line 'Start Windows in last known good configuration'. Use the up and down arrow keys to select this, then hit 'Enter'. Again, after a few minutes, Windows will start and it should be running normally.
It may be that Windows' idea of 'Last known good . . .' is not the same as yours. In which case repeat the process with the 'F8' key, but this time choose 'Repair options'. After about 5 minutes, again, it may have fixed the problem, it may not. If not, you will be offered 'Advanced repair options' and through this you will get back to the 'Choose a restore point options'. At this point continue as in the first solution !
After you have done this, you will have to re-install any updates since the restore point chosen. Since it could be one of these that caused the problem, I suggest installing them one at a time.