Okay, the problem is solved now. I downloaded both intel and amd drivers from links you provided which was from dell website but unfortunately when trying to update intel driver I got the error saying the operating system isn't supportive.  So the solution I found for this was, I visited the intel website, searched the graphic driver, which was intel hd graphics 620 for my pc, downloaded the zip file because .exe file may show the same error again. Extracted this zip file to a new folder. Next I opened device manager, clicked on the display adaptors, right clicked on intel and selected update, then manually chose the location to find the file to upgrade the driver, selected the folder where the zip file was extracted and the update was done.  Then I used the amd exe file downloaded from the dell website and I was able to reinstall the amd driver back to how it was.  But one thing I noticed was, before updating the amd driver was named as HD 8500M and after updating the name changed to R5 M420, checked on google and found it was just a renaming done to it, so no issues with it. Finally, thanks a lot for the support, I really appreciate it. 
Hello, today was the first time I used the support assist software on my laptop after 4+ years of using my laptop, there were some driver and critical upgrades, installed them all, later I happened to install Radeon graphic driver from website but during the support assist upgrades it had installed but I happened to do it again through their website, so I uninstalled it and checked the support assist app to see if there was graphic update but I don't see, so what do I do?
Installing graphic driver