sushantdas,

If it has been less than 30 days you should be able to restore to Windows 7 by going into safe mode. Start the computer and tap the F8 key. Once the advancecd options appear on the screen you can choose safe mode. Once in safe mode go to settings and click on update and security. Now tap or click on the Recovery option in the menu on the far left of your screen. It’s just below the Backup menu item. Click on Go Back To Windows 7 and follow the prompts.

Follow the instructions here to Download a Windows 10 RS1 .iso and Clean Install:

http://dellwindowsreinstallationguide.com/download-windows-10-oem-and-retail-iso/ 

"If it has been less than 30 days you should be able to restore to Windows 7 by going into safe mode. "

Does not always work. Failed on my when I upgraded my Inspiron 3542 the first time. I used Acronis True Image before the upgrade.

Hi,

I was able to go back to my Windows 7 Home Edition. Now new issues arise. First I am unable to update it to SP1 as the windows update fails to install KB976932. Apart from this, I am unable to create usb recovery from dell data safe local backup as both the options are coming greyed out.

Dell DataSafe is long obsolete. Install the latest version of Dell Backup and Recovery which should apply some fixes. Use it to make Recovery Media. See here:

http://dellwindowsreinstallationguide.com/dell-backup-and-recovery-1-8-1-71/